SSON Update on Comet ISON

Posted on March 5, 2013 by Rich Williams

By Rich Williams

I took a series of 180-second exposures of Comet ISON using the Sierra Stars Observatory telescope in California last night (evening of March 4th California time/ March 5th UT date) to see how the comet was behaving. The comet hasn’t shown much of an increase in its brightness or in the length of its tail since my last blog about the comet on February 11. However, it is still out around the orbit of Jupiter and has a ways to go before approaching the sun.

Below is a composite image of Comet ISON created from seven 180-second images for a total of 21 minutes of exposure time. The telescope was guiding on the comet during the exposures. The comet is in the center of the 21 x 21 arc-minute field of view of the image.

Comet ISON March 5, 2013

The image below is a zoomed in area of the comet from the image above.

Comet ISON March 5, 2013 — zoomed in

Finally the video below shows the comet moving through a crowded star field in the constellation Gemini\. You can see a few galaxies in the images as well. The total time from beginning to end of the sequence is about 40 minutes. The tail seems more apparent in this moving image of the comet.

Comet ISON Video March 5, 2013

Comet ISON Shows Its Tail!

Posted on February 13, 2013 by Rich Williams

By Rich Williams

I decided to start chronicling the changes in comet ISON as it approaches perihelion and beyond. On the night of February 12, 2013 UT date (Monday night February 11 California start time). I scheduled a series of 12 180-second images of ISON using on the SSO 0.61-meter telescope here in Markleeville, California. The seeing varied between 2.0 to 2.4 arc seconds that night. The telescope tracked on the comet selected from the SSON online MPC database. I downloaded my images from my SSON FTP directory after processing the SSON jobs for the night’s observing run. On first inspection I was delighted to see a discernible tail on the comet. This is pretty cool as the comet was still just beyond the orbit of Jupiter and more than 9 months from its extremely close grazing of the sun when it reaches perihelion. Comets coming out of the Oort are fresh and very unpredictable. Even so I think that an early tail like this is a good sign for a great show this fall and winter.

Comet ISON showing early signs of tail.

I processed the 12 images using MazIm DL to create a movie loop of the series. Other than stretching the calibrated images no image processing was performed on the data. Above is one of the 180-second images of the comet. The field of view is approximately 21 by 21 arc minutes. The magnitude of the comet was approximately 15. The comet, while small, clearly shows a tail in the full image. The image below is a zoomed in cropped area around the comet from the same image.

Comet ISON zoomed in view

Finally the video below is a movie loop of the 12 images clearly showing the movement of the comet against the star field over approximately 40 minutes. I will try to image the comet regularly (every week or so weather and moonlight permitting) to monitor the brightness and changes in the comet as it approaches the. Sun. I’ll post my results here on this blog for you to see.

Comet ISON Video 2/12/2013

Learning How to Use the Rigel Transmission Grating Spectroscope (TGS)

Posted on January 21, 2013 by Rich Williams

By Alessandro Odasso

The Rigel Telescope Transmission Grating Spectroscope (TGS) system has been made available to the SSON users thanks to the cooperation between Rich Williams and Dr. Robert Mutel (Iowa University). Quoting Rich’s words “The Rigel Telescope TGS system opens up a whole new field of inquiry for students, researchers, and curious people”.

I belong to the third group and I must say that when I first read his blog I was not only curious but also a bit puzzled. I was curious because I knew that the spectrum of a star is like a fingerprint, in a metaphoric sense it’s like the star’s own DNA. I was a bit puzzled because I was afraid that such a system would be too complicated to be used by a user with no specific experience.

During the Christmas holidays I decided to devote some time to read once again the blog and to pay attention to the user manual written by Dr. Mutel and I felt that, after all, it did not sound as complicated as I initially feared.

My first attempt in using the system was aimed at getting the spectrum of Merope, a star belonging to the Pleaides cluster. To do so required me to do two things:

1) I took an image of Merope(30 seconds exposure time)

2) I analyzed the FITS image with two different programs.

Phase 1 – Taking an Image

I decided to use the S filter, the one that has a slit to block out most light except for a narrow strip. You schedule to take TGS images on Rigel just as you do for regular images. However, you need to define two other parameters:

The first parameter, “focus offest” is intended to tell the system which part of the spectrum you want to analyze with greater resolution. Having nothing specific in mind, I chose 402, a value that allows you to observe the H-alpha line with maximum spectral resolution.
The second parameter, “RA offset” is a correction factor intended to have the star displayed on the left side of the image, just a trick to have the elongated black and white rainbow spectrum centered in the middle of the image. Again, not a problem: the manual gives you a very simple formula that calculates the RA offset, already expressed in RA seconds, taking into account the star declination.

Maybe, in the future, the SSON web page could be programmed so that this calculation is done automatically.

There is nothing different about the resulting FITS image. FITS is a standard so you can open the image with whatever FITS viewer, including Astrometrica (by H. Raab): you clearly see the spectrum spreading at the right of the slightly defocused zero-star and you can read the usual details in the FITS header.

Phase 2 – Analyzing the image and displaying the spectrum

My initial attempt to analyze the spectrum in my image was with RSpec, whose trial version can be freely downloaded from the vendor site.

I was impressed with RSpec’s very easy installation and very nice Graphical User Interface. Even without reading the manual, it is straightforward to open the FITS file and you are immediately rewarded by the system that displays a raw, not calibrated spectrum. In other words, the system displays a graph where the Y axis is related to the pixel brightness and the X axis represents the various pixels of the spectrum that you see in the FITS image.

The next step is to calibrate the graph so that the X-axis represents the wavelength expressed in nanometers (or Angstroms). The easiest calibration supported by the program is the one where you simply fill a field telling the system how many Angstroms / pixels must be taken into account. But here I was at a loss; I had no idea about the correct value!

The calibration technique is explained well in the video tutorials provided by RSpec. The idea is to identify a specific spectrum feature by simply clicking on it and by giving it the wavelength that you either know a priori or that you can get by clicking on the correspondent feature of a reference image of a star having a similar spectrum. The nice thing is that RSpec is shipped with a large reference library of star spectra.

As easy as this may seem, when I used the reference spectrum B6IV that should have worked with Merope… again I was at a loss! When I opened the spectrum of the reference image I was unable to compare it with my raw spectrum: the shapes were too different and I couldn’t determine which features matched in the two spectra!

At this point, to be honest, I felt confused. My learning curve was greater than I expected. While this learning process is certainly important, it is a bit frustrating, especially if you are a bit lazy as I am

But here I have good news! Another nice thing about RSpec is that there is a Yahoo RSpec User Group where you can ask for help! This is a place where many technical issues are discussed and clarified. So I joined the forum and I am pleased to say that they helped me immediately sending me a calibration file that was a good starting point.

I guess the reason why RSpec calibration process is not automatic is simply due to the fact that RSpec needs to be very general, the software is not tailored to any specific hardware platform.

Rigel TGS Software for Linux and Mac Operating Systems

When I contacted SSON and Dr. Mutel asking for help calibrating my TGS images, I was given software that is designed specifically for use with the Rigel TGS. Almost no calibration is needed. This software comes in the form of a Python script that requires a Linux installation. I was lucky in this case as I happen to have a dual boot system with Debian installed on my computer.

Before running the script, I had to install a few libraries according to the instructions that I received. The whole installation process took less than 30 minutes and it was straightforward.

The nice thing about the program is that it is able to generate a bitmap showing the calibrated spectrum plus specific spectrum features in a complete automatic way and in just a few seconds!

You do not have to bother about details like, for example, the graph title and exposure time: this information is generated reading the data from the FITS file. Furthermore, you can choose which spectrum features you would like to be highlighted. Finally, the program is able to synthesize a second bitmap image of the colored spectrum rainbow. There is one important input that you must be careful to identify and enter: the zero-star pixel position.

The image below is the Merope spectrum that I obtained a few minutes after the installation of Dr. Mutel’ script:

My experience proved to me that Dr. Mutel’s TGS software program is easy to use. It is only fair to note that when something like this is easy to use the reason is because other people spent a lot of time and effort to design and implement it. We must praise the Iowa and SSON teams for this!

Of course, this new tool does NOT transform us “curious people” into experts! However, thanks to this new tool and with appropriate guidance from professionals we may be in the position to give a little but not negligible scientific contribution in the framework of the so called pro-am collaborations or “citizen science projects”.

_________________________________________________________________________

Alessandro has been an avid SSON user since November 2009. He participates in several astronomy programs and projects. I thank him for giving me his personal experience using the new Rigel remote TGS system and sharing it on my blog.

I also would like to thank Dr. Mutel for his continued excellent work on the Rigel TGS system. He wrote the code for the Rigel TGS Software and continues to enhance it with features such as TGS Stitch, which enables you to combine two or more spectrum data optimized for different wavelengths into a single data graph. It’s very cool and useful!

For those of you who want to run the Rigel TGS software on a Windows system you can install the Ubuntu Linux operating system on Oracle VirtualBox. Both VirtualBox and Ubuntu are free to download. I have this set up on the Windows 7 laptop I’m writing this with. It’s easy to do following the installation instructions for both programs. After setting up Ubuntu (or another Linux OS) on VirtualBox, download the TGS Software and install it according to Dr. Mutel’s instructions.

Here are some links to quickly get you started installing the Rigel TGS Software on your system:

– Rich WIlliams

Scientific Astrophotography Book Review

Posted on December 31, 2012 by Rich Williams

Jerry Hubbell first started using SSON for his astronomy projects in April 2009. Three years later in April of this year Jerry sent me an email message asking if I would be willing to review a draft of an astronomy book he was writing that would be published later this year by Springer for Patrick Moore’s Practical Astronomy Series. The title of Jerry’s book is Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data.

I was very impressed with Jerry’s hands-on approach to the subject and to his excellent presentation and organization. After reading the draft I wrote the following review of the book for Jerry:

“Jerry Hubbell has been using SSON since April 2009 for various remote astronomy projects. His new book “Scientific Astrophotography” is a well written, comprehensive description and guide for doing meaningful scientific imaging work in astronomy. Whether you are just starting out or are experienced doing scientific astronomy projects you will find the book to be an excellent reference for improving your skills.”

Scientific Astrophotography is a great “How To” book. Jerry takes a somewhat engineering approach to the subject. In the final chapter in the book, Amateur Astronomer Access to Professional-Level Observatories, Jerry wrote a very nice section called Using the Sierra Stars Observatory Network (SSON).

Congratulations Jerry on a job well done! I look forward to reading the next book you are writing.

– Rich Williams

Near-Earth Asteroid Toutatis Video

Posted on December 13, 2012 by Rich Williams

Adam Block took a series of images of the near-earth asteroid Toutatis as it passed close by Earth using the Mt. Lemmon Sky Center Schulman 0.81-meter telescope. The images were taken on December 11 around 7PM MST (2:00 UT December 12).

The video combines 180 5-second exposure images taken back to back. The total elapsed time in the video is 15 minutes. The asteroid was moving quite fast against the background stars at the time!

Adam is the manager of the Mt. Lemmon Sky Center Observatory and oversees the operation of the observatory within SSON.

Thanks for sharing Adam!

– Rich Williams

Remote Spectroscopy of a Wolf-Rayet Star Using SSON

Image

Before releasing the Rigel Telescope transmission grating spectroscope (TGS) system for use by SSON users I had to run some tests of the system to ensure it worked well. I chose to run a series of schedules on the Wolf-Rayet (WR) star HD 50896 also referred to as WR6 from the Wolf-Rayet catalog. Wolf-Rayet stars are very rare, only about 500 Wolf-Rayet stars are known in the Milky Way galaxy. They are the massive stars that start out their life with a mass more than 20 times the sun. They are also extremely hot stars with surface temperatures ranging from 30,000 to 200,000 degrees Kevin.

WR stars burn through their hydrogen fuel very rapidly ending their lives in a supernova explosion after only a few million years. During their life they eject huge amounts of gas creating a kind of atmospheric shell surrounding the star with a mass that eventually can equal that of the star. The light we see from these stars is actually mostly visible light emitted from the heated, excited ionized gas shell. This is what makes them such interesting objects to study with a spectroscope.

As the WR stars evolve towards the end of their life the composition of the gases in the surrounding envelope changes from mostly helium and nitrogen to more carbon and oxygen. This change in composition over time is the reason WR stars fall into two main classifications: WN sequence of stars with broad emission lines of helium and nitrogen and WC sequence stars with broad emission lines of helium, carbon, and oxygen.

Although they are extremely hot and bright most of the photon energy released by WR stars is in the form of UV and soft X-ray light, which is what excites the ionized gas in the shell. The only WR Star easily visible to the naked eye is Gamma 2 Velorum, which is a 1.7 magnitude star located in the southern hemisphere. Because the Rigel TGS disperses the light of a star (or other object) you need to image relatively bright objects to achieve reasonable signal to noise ratio data in reasonably short exposure times. For my test of the Rigel TGS automated run I selected the WR star HD 50896 because at a V magnitude of 6.74 it is a fairly bright target for the Rigel TGS to image. The images were taken the night of November 27, 2012 UT, two days before a full moon.

Figure 1. TGS Image of Wolf-Rayet star WR6 taken with SSON/Rigel Telescope

Figure 1 illustrates what the original calibrated FITS files data looks like. I set the SSON schedule to use the S filter on the Rigel Telescope, which is the 600-line TGS filter using a slit to block out all but a slice of the sky around the star. The slit is useful for blocking out extraneous light from nearby spectra in crowded fields. However, the alternate non-slit TGS filter on the Rigel telescope works as well in most cases. The exposure time of the image is 120 seconds. As you can see the stars are deliberately defocused to give a better spread of the dispersion for measurement. The object star is deliberately positioned at the far left side of the image to capture the complete spectrum to the right.

After you receive your image spectrum data you need a software program to measure and analyze it. I used an excellent software program called RSpec to analyze my data. It runs on Windows and is easy to learn and use. You can download a fully functional 30-day trial version to try it out before buying.

Figure 2. Spectrum graph of WR6 from data in figure 1 created with RSpec

Figure 2 shows the calibrated measured spectrum of the image data in Figure 1. The very strong helium II emission line in the spectrum of the Wolf-Rayet star clearly stands out in the top graph. On the bottom is a synthesized color spectrum of the monochromatic data. One of the reasons I chose a Wolf-Rayet star is because these stars are some of the few stars that show such strong emission lines in their spectrum. The emission comes from the hot excited ionized elements in the gas shell surrounding the star. The spectra of the vast majority of stars primarily show absorption lines that are black caused by colder gas blocking and filtering the light. Figure 3 shows the spectrum of Vega from the data taken with the Rigel TGS that shows many absorption lines (note that the peaks in the graph are inverted compared to the emission lines in the WR spectrum, which point upwards).

Figure 3. Spectrum of Vega measured with Rigel TGS system

Dr. Mutel, the mastermind behind the Rigel TGS system at the University of Iowa, analyzed the spectrum of the same image I did using a Linux-based software program generating a graph very similar to the one I created using RSpec. He overlaid markers for the emission lines of several of the elements that appear prominently in the WR spectrum. You can see the results in Figure 4. It is fascinating that you can read the complex chemistry of a star this way.

Figure 4. Graph of spectrum of WR6 highlighting element emision lines

If you decide to try out the SSON/Rigel TGS system be forewarned that you will have to do a little more work beforehand than you do using the regular photometry and color filters in our system. You need to determine which wavelengths of the spectra you want to optimize and calculate the appropriate offsets. This is explained in the scheduling section of the SSON web site and in the TGS Users Guide that Dr. Mutel wrote, which you can also download from the web site.

You have the option to use two TGS filters on the Rigel Telescope. They are identical 600-line TGS filters but one has a slit to block out most light except for a narrow strip. The other filter has no slit and is great for imaging extended objects and getting multiple spectra in a single image. Both TGS filters produce excellent results.

The Rigel Telescope TGS system opens up a whole new field of inquiry for students, researchers, and curious people. I look forward to seeing and hearing about how our users take advantage of this great opportunity to do spectroscopy projects remotely using SSON.

- Rich Williams

Update on Rigel/SSO NEO Parallax Project

Posted on November 1, 2012 by Rich Williams

Below is an update from Dr. Mutel on the NEO parallax measurement project run jointly using the University of Iowa Rigel Telescope in Arizona and the Sierra Stars Observatory in California last September. I wrote about the project in the blog post A Project to Measure the Parallax of Asteroid 2012 QG42 Using the Sierra Stars Observatory Network.

– Rich Williams

In September we set up a 2-telescope parallax observation to measure the distance to an NEO which was near closest approach. We used Rigel and the Sierra Stars Observatory 24-inch in California. The attached document details the data analysis and the result, which was within 4% of the JPL Horizons distance at the time of observation.

This is a great project for the more advanced astronomy labs (General Astronomy, Astronomical lab), although it requires knowledge of spherical geometry.

– Dr. Robert Mutel

How I Discovered Comet Vorobjov

Posted on October 22, 2012 by Rich Williams

By Tomas Vorobjov

October 15, 2012. It was a bit of an unusual Sunday. It had been some time since ARI (H21) was clouded out on Sunday which meant no NEOCP follow-ups to measure. I kept refreshing the view of my SSON FTP folder almost every minute for an hour or so, waiting for files from 8 jobs to be uploaded. The same eight jobs we originally scheduled for the Saturday night but the Mt. Lemmon SkyCenter telescope was used for local operations by visiting astronomers. Therefore, I had to move the jobs to Sunday. If the Schulman Telescope (G84) had been running for SSON on Saturday I would most likely not be writing this article right now.

The purpose of the scheduled observations was to gather data for minor planet search in one of the school campaigns organized by the International Astronomical Search Collaboration (IASC). The IASC is an education outreach program started by Dr. Patrick Miller in October 2006 at Hardin-Simmons University (Abilene, Texas).

Through this program high school and college students make original discoveries of Main Belt asteroids. IASC collaborators include Pan-STARRS (University of Hawaii – F51), Astronomical Research Institute (Westfield, IL – H21), the Xinglong Station (National Astronomical Observatories of China – 327), and since September 2012, we’ve been also using the Mt. Lemmon Sky Center (G84) through SSON. We get survey image sets from these observatories and the IASC Data Reduction Team (IDaRT), of which I’m the director, handles the image analysis. I compile and send a report to Minor Planet Center (MPC) with our discoveries (so that we get measurements in as soon as possible). We then distribute the images to schools via the Internet. When students identify objects in these images, the discovery credit is shared with them and they are offered to suggest names for objects once a permanent designation (number) is assigned. Over the years, students in IASC asteroid search campaigns have made 500+ provisional discoveries reported to the Minor Planet Center, including 15 numbered asteroids being named by their student discoverers. There have been two NEO discoveries including one potentially hazardous asteroid (PHA) along with one Jupiter Trojan discovery.

In September 2012, IASC started using the Schulman Telescope at the Mt. Lemmon Sky Center (G84) to gather survey images for the All-China Asteroid Search Campaign. During six nights (Sept. 18, 19, 21, 23, 24, and 26) we gathered survey images from 68 fields (each field is approximately 20′x20′), measured and reported 142 objects and discovered 27 new minor planets which now have received a provisional designation from the MPC.

Plot of the sky coverage by G84 between September 18 and 26, 2012

After a short break due to the brighter and brighter Moon and a transient cloud cover the plan was to restart the survey during the weekend of 14/15 Oct. The area of the sky to scan is not chosen randomly; there is a bit of reasoning behind the selection process. The best location to scan for new main belt asteroids is close to the ecliptic and up to about 2 hours in the right ascension (RA) ahead of the opposition point. Due to the opposition effect, undiscovered objects may brighten enough to be observable with a relatively short (60-120s) exposure. The constraints to stay close to the ecliptic and ahead of the opposition point reduces the suitable “real estate” for our survey to about 600 square degrees. The second important aspect to consider is the area of the sky observed by other observers. Ideally, the survey should scan an area not visited by another observer at least during the current lunation. As our survey aimed to reach objects down to magnitude 21, of which G84 is capable with about 120s single exposure, the only other observers needed to be considered are the major sky surveys: Catalina Sky Survey (703), Mt. Lemmon (G96), Pan-STARRS (F51) and Spacewatch (691, 291). The Sky Coverage service provided by the MPC comes quite handy here. All these surveys submit their sky coverage data to the MPC usually at the end of an observing night so anyone can see which areas of the sky have been surveyed (and when).

Sky coverage plot displaying areas of the sky surveyed by the major sky surveys between Oct. 8 and 15, 2012

Examining the sky coverage plots to find the best area to survey, there didn’t seem to be any suitable “real estate” within 2 RA hours of the opposition point. There was a plenty of unobserved sky about 1 RA hour past the opposition point but observing there would be of low value. First of all, objects in that area of the sky are already becoming fainter and fainter (leaving the opposition effect) as the phase angle is increasing. Secondly, a vast majority of these objects have most likely been already observed at least during one night in the last 2-3 months when they were brighter (closer to the opposition point).

The area that most closely met our requirements was a relatively small patch of the night sky, about 4×4 degrees, between a declination of 12 and 16 degrees north past the RA 03:30. As the last step in the sky area selection process I did a relatively fast and simple check:

First, I used the MPChecker service to find a few dozen known main belt objects currently located in the area of the night sky. Then, I entered a list of these designations into the Minor Planet & Comet Ephemeris Service, which apart from the ephemerides also displays the date of the last observation.

Looking at the last observation date for virtually all of the known objects showed that none of them have been observed during the current opposition. Assuming that unknown main belt objects would be moving at approximately the same speed and position angle (PA) as the known ones, and given that none of the previously observed objects have been seen during this opposition, there is a very good chance most of the unknown objects would not have been observed either.

I scheduled 8 jobs to run at the Mt. Lemmon SkyCenter Schulman Telescope (G84) with coordinates RA 03:30:45 (45 RA seconds is a little less than half of the field of view so the edge would start just before RA 03:30) and the declination from +13:10 to +15:30 in 00:20 steps (the field of view is just a little of 20 arc-minutes, leaving a nice little overlap between the images in the series).

The sky covered by the G84 survey jobs on October 15, 2012

After downloading the images from October 15 it was immediately obvious the observing conditions were great. Objects down to magnitude 21.5 were detectable on these 120s exposures; seeing was sub-arc second. Nothing seemed extraordinary throughout the first five sets. There were 20 unknown objects ranging from V19.5 down to V21, all moving with the speed and PA similar to known main belt objects in this portion of the sky. In the sixth set, as I found another moving object, I proceeded with a familiar routine:

Determine if there is a known object at these coordinates
The object was unknown, so check which observer’s temporary designation was next in line

I marked the object as TOV7DD on all three blinking images and was about to move on when I noticed a tail-like feature happily riding along with what turned out to be a nucleus of the comet.

P/2012 T7 (VOROBJOV) discovery sequence from SSON/Mt. Lemmon telescope data.

As the tail was barely visible I decided I wasn’t 100% sure it wasn’t just a CCD artifact playing a cruel joke on me. Therefore, I reported the object as stellar to MPC and kindly asked Bob Holmes at the ARI observatory (H21) to image the target the following night. When images from H21 arrived, it was immediately obvious that TOV7DD was a comet with an elongated coma and a very nice 20-30″ long tail in PA about 265 degrees. Sergio Foglia who was analyzing and measuring other NEO Confirmation Page (NEOCP) targets observed at H21 that night arrived at the same conclusion about the nature of TOV7DD and reported it as a new comet to both the MPC and CBAT.

Confirmation of comet-like features of TOV7DD taken by R. Holmes (H21)

Because the NEO rating for TOV7DD was only 12, Gareth Williams from the MPC had to manually add it to the NEOCP. Consequently, I informed Gareth about the discovery observations from G84 from the night before and he updated the NEOCP manually again (rather than to wait for the automated routine to make the link after more observations have arrived).

After posting on the NEOCP webpage, other observers have found TOV7DD’s cometary features.

Stack of four 40-second exposures taken by Andrea Boattini at the Mt. Lemmon Sky Survey (G96)

Confirmation image taken by Nick Howes, Giovanni Sostero & Ernesto Guido from Faulkes North (F65)

The discovery of comet P/2012 T7 (VOROBJOV) was announced by the Minor Planet Center on 18 October, three days after the discovery. The preliminary orbit placed the comet into the Jupiter comet family.

Orbital elements:
P/2012 T7 (Vorobjov)
T 2012 June 16.58408 TT                                 MPC
q   3.7859963            (2000.0)            P               Q
n   0.07238300     Peri. 174.76846     +0.88063332     -0.45594956
a   5.7022333      Node   213.34342     +0.42575877     +0.88082526
e   0.3360503      Incl.   13.55433     +0.20788081     +0.12750238
P 13.6
From 46 observations 2012 Oct. 15-18

Preliminary orbit of Comet P/2012 T7 (VOROBJOV) based on observations between Oct. 15 and Oct. 18, 2012. Orbit is generated using the Orbital simulation applet provided by NASA.

Tomas Vorobjov

I was born on March 4, 1984 in Bratislava, Slovakia. I got my high school diploma at the United World College of the Adriatic (Duino,Italy) and a BA in Computer Science and Math at Colby College (Waterville, ME). After graduating from Colby (2006) I worked as a web application developer in New York, London, Amsterdam and back in London until July of this year when I moved back to Slovakia. In 2010 I joined the IASC and later became the director of the Data Reduction Team (IDaRT).

Comet Vorobjov Discovered Using SSON!

Posted on October 18, 2012 by Rich Williams

Comet Vorobjov discovery sequence from SSON/Mt. Lemmon telescope data.

Below is an announcement sent out today by Patrick Miller, founder of the IASC program about the discovery of Comet Vorobjov. Tomas Vorobov discovered the comet on an SSON observing run using the Mt. Lemmon 32-inch telescope in Arizona.Sunday night (October 15 UT date). Tomas has agreed to write a guest blog for my SSON Remote Astronomy Blog about his discovery experience. He’ll probably need a little time to wind down now though.

I imaged the comet the following night using the SSO telescope in California. The data helped with the orbit determination of the periodic comet.

Congratulations Tomas!

– Rich Williams

Comet Discovery!!

Tomas Vorobjov directs the IASC Data Reduction Team (IDaRT). This past week while processing IASC images taken at the Sierra Stars Observatory Network (0.81-m Mt. Lemmon) he discovered a new comet. He reported the discovery to the Minor Planet Center. A number of the IDaRT support sites immediately sprang into action to take confirming follow-up images… ARI, SSON, Schiaparelli, Faulkes.

This afternoon the MPC officially announced the discovery, P/2012 T7 Comet Vorobjov. Congratulations, Tom. Outstanding work!!

Last year while working with images for IASC and the ARI, Tom discovered a trans-Neptunian object (TNO), 2012 HH2. This object is about 200-km in diameter and sits out near Pluto.

Dr. Patrick Miller

A Project to Measure the Parallax of Asteroid 2012 QG42 Using the Sierra Stars Observatory Network

Posted on September 17, 2012 by Rich Williams

A Project to Measure the Parallax of Asteroid 2012 QG42 Using the Sierra Stars Observatory Network

by Rich Williams

Many college and university professors use SSON for astronomy education and research projects. Professors and their student often come up with innovative ideas for projects. Dr. Mutel and his students at the University of Iowa saw a great a great opportunity for an interesting project with the close approach to the near earth asteroid 2012 QG42 early on Saturday night September 15 local time in the western United States (September 16 UT date). The closest approach of the asteroid was actually on the Thursday night. However, the Rigel telescope in Arizona, which was to be one of the two telescopes used for the project, did not resume operation from the monsoon season closure until Saturday night.

The project goal was to measure the topocentric parallax of the asteroid between two widely separated telescopes and thus determine distance of the asteroid. The procedure for measuring the distance to an asteroid using the parallax method is straightforward:

Choose two or more telescopes located at widely separated locations for the baseline of the parallax measurement. In this case, the telescopes used were the Rigel Telescope in Sonoita, Arizona and the SSO telescope In California. The baseline distance between the two telescopes is approximately 700 miles (1127 kilometers).
Take a series of images of the asteroid simultaneously with exposure times long enough to achieve a sufficient signal to noise ratio for precise astrometry measurements of the asteroid.
Measure the position of the asteroid in right ascension and declination in each of the corresponding images from both telescopes.
Using trigonometry with the baseline distance and the angle of the triangle measured in arc seconds from the parallax measurements determine the distance of the asteroid at the times of the exposures.

The procedure for measuring the parallax of an asteroid is simple in principle; however, the challenge is to ensure that you attain images from the participating telescopes as nearly simultaneous as possible. To resolve this issue Dr. Mutel and his students at the University of Iowa came up with the idea of running a series of exposures on each telescope with a 10-second offset in the start times of each exposure in the series. The idea was that even though our start times were unknown, over time the differential between the times would converge closely at some point. Starting around the same time each telescope ran a series of approximately 100 images. The Rigel telescope took 30-second images every 70 seconds while the SSO telescope took 20-second images every 60 seconds. Because the SSO telescope has a larger aperture than the Rigel telescope it required shorter exposure time to achieve a similar signal to noise ratio.

Both telescopes were tracking the fast-moving asteroid, which had a highly non-sidereal angular speed of 0.6 arcsec/sec. The asteroid magnitude at the time was V = 16.2. – the stars are streaked because the telescopes were tracking the asteroid. The parallax is very obvious, about 1 arcminute.

The image at the top of this blog shows the resulting parallax measured by the telescopes from two of the images separated by 2.5 seconds in time from a preliminary review of the data. The students are analyzing the data in more detail and will likely find other corresponding data that are even closer in time separation.

This type of project with real-world timely data makes SSON a fantastic tool for astronomy education and research programs. Here is a quote from Dr. Mutel after successfully getting the results from the parallax project: “We are doing these observations to develop a new research project for astronomy lab students: direct measurement of NEO close encounter distances.” Many professors use SSON for their astronomy labs and research projects find SSON to be a valuable tool and the list is growing. This is very satisfying as my goal in starting up SSON back in 2007 was to make professional observatory systems accessible and affordable for college and university astronomy programs.