Monthly Archives: January 2016

3453 Dostoevsky

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After taking a few comet images from Slooh.com recently, I came across a group there called the A-Team that observes and reports on minor planets – particularly Near Earth Objects or NEOs. Through this group, users can gather observations and report them to the Minor Planet Center after completing a tutorial syllabus and qualifying for submissions. I was very excited to find out about this resource, as I have been wanting to contribute to this field but really do not have the conditions and equipment to do this from my own back yard!

I don’t want to cite or reproduce the A-Team pages from the Slooh site but can mention some of the public resources the group suggests and results of some early observations.

To start, they recommend taking observations on a few brighter objects, and this is what the Minor Planet Center also requires before qualifying for a new observatory code. To help identify some candidates, I went to the JPL SB Whats Observable site. You can enter a time and location and other parameters such as a magnitude cut-off and get a list of minor planets and comets observable at a given location.

I put in the parameters of interest and generated a list of over 2000 objects! Did not see a download option but was able to take the list, save it to a file and coax it into Excel. From this list I identified some targets around mag 15 and selected a subset of the sky that would be at a good elevation – and also away from bright Jupiter and crowded star fields in the Milky way.

Many choices were available, but my eye caught 3453 Dostoevsky, whom I always enjoyed reading in college – plus evoking Mel Brooks’ The Twelve Chairs. At an expected magnitude 15.8 this looked like a reasonable choice to try.

I booked sessions at the Slooh Canary Island site but was thwarted by clouds for a few days, but then managed to get some images from their site near Santiago, Chile. I scheduled 3 sessions 30 minutes apart. The first time point looked fine but the second showed pretty severe streaking. The third set looked OK so I went with the first and third exposure times.

After entering the telescope, camera and analysis parameters recommended for the site, Astrometrica solved the images nicely and identified a clearly moving bright object as 3453 Dostoevsky with these values:

 

03453         C2016 01 15.29433 08 37 33.89 +18 20 19.2          16.0 V      W88

03453         C2016 01 15.33310 08 37 31.45 +18 20 23.6          15.9 V      W88

To check observations, the group recommends using an online tool for calculation residual values at fitsblink.net. After loading the above this site returned:

(3453) = (03453)
1. 03453 C2016 01 15.29433 08 37 33.89 +18 20 19.2 16.0 V W88 -0.16 -0.03
(3453) = (03453)
2. 03453 C2016 01 15.33310 08 37 31.45 +18 20 23.6 15.9 V W88 -0.09 +0.12

This shows differences in the measured and expected coordinates of less than 0.2 arc seconds, so it looks like I have the right object!

Next I tried choosing a fainter target and found a pair of minor planets well below mag 16 and quite close to each other: 3900 Knezevic and 2287 Kalmykia. The Chile observatory was booked up, so I set up 3 times at CI spaced about 40 minutes apart. The weather cleared up that night and I got 3 sets of very nice image files.

If you have 3 or more files from a given location, Astrometrica can reduce the images and look for objects that have a consistent displacement across the set. This identified 4 moving targets in the frames! These looked good from visual inspection, and no other moving objects could be clearly seen. (There were a number of single hot spots and streaks that were likely artifacts).

The expected targets were seen, as well as 2360 Volgo-Don at mag 16.6 and 32729 “5179 T-3” at mag 17. Volgo-Don was at the edge of the frames but clearly seen in all 3 images so this looked to be real.

So here we have 4 objects and 3 times or 12 observations from Astrometrica

02287 C2016 01 17.20921 09 39 10.29 +19 25 12.5 16.8 V G40
02287 C2016 01 17.24113 09 39 08.71 +19 25 24.9 16.8 V G40
02287 C2016 01 17.27185 09 39 07.19 +19 25 36.6 16.8 V G40
02360 C2016 01 17.20921 09 41 16.58 +19 26 19.0 16.7 V G40
02360 C2016 01 17.24113 09 41 15.08 +19 26 27.7 16.6 V G40
02360 C2016 01 17.27185 09 41 13.64 +19 26 36.3 16.7 V G40
03900 C2016 01 17.20921 09 39 45.51 +19 23 09.8 16.9 V G40
03900 C2016 01 17.24113 09 39 43.75 +19 23 14.2 16.7 V G40
03900 C2016 01 17.27185 09 39 42.07 +19 23 18.8 16.9 V G40
32729 C2016 01 17.20921 09 40 01.34 +19 17 13.1 16.9 V G40
32729 C2016 01 17.24113 09 40 00.46 +19 17 31.8 16.9 V G40
32729 C2016 01 17.27185 09 39 59.61 +19 17 49.7 17.0 V G40

Running these through Fitsblink gave:

(2360) = (02360)
   1.  02360         C2016 01 17.20921 09 41 16.58 +19 26 19.0          16.7 V      G40    -0.14    +0.07
(2360) = (02360)
   2.  02360         C2016 01 17.24113 09 41 15.08 +19 26 27.7          16.6 V      G40    -0.04    +0.06
(2360) = (02360)
   3.  02360         C2016 01 17.27185 09 41 13.64 +19 26 36.3          16.7 V      G40    +0.00    +0.31
(2287) = (02287)
   4.  02287         C2016 01 17.20921 09 39 10.29 +19 25 12.5          16.8 V      G40    -0.13    +0.02
(2287) = (02287)
   5.  02287         C2016 01 17.24113 09 39 08.71 +19 25 24.9          16.8 V      G40    -0.03    +0.12
(2287) = (02287)
   6.  02287         C2016 01 17.27185 09 39 07.19 +19 25 36.6          16.8 V      G40    -0.01    +0.01
   7.  32729         C2016 01 17.20921 09 40 01.34 +19 17 13.1          16.9 V      G40    -0.17    +0.08
   8.  32729         C2016 01 17.24113 09 40 00.46 +19 17 31.8          16.9 V      G40    -0.06    +0.12
   9.  32729         C2016 01 17.27185 09 39 59.61 +19 17 49.7          17.0 V      G40    -0.14    +0.12
(3900) = (03900)
  10.  03900         C2016 01 17.20921 09 39 45.51 +19 23 09.8          16.9 V      G40    -0.10    +0.16
(3900) = (03900)
  11.  03900         C2016 01 17.24113 09 39 43.75 +19 23 14.2          16.7 V      G40    -0.13    -0.03
(3900) = (03900)
  12.  03900         C2016 01 17.27185 09 39 42.07 +19 23 18.8          16.9 V      G40    -0.07    +0.20

Some variability, but all except one are under 0.25″. It looks like this telescope and camera yields accurate positions across the whole image frame!

The following animated GIF shows 3 of the objects closest to the center:

20160118-3900-blink-animation-r

Good fun! Next step will be to taking and stacking longer exposures to try to detect some of the many fainter objects out there.


					

		
		
	


				
					
	

		

						
C/2013 US10 Catalina

			
						

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Comet Catalina C/2013 US10 is currently visible in the Northern Hemisphere using binoculars or a small telescope. After rounding the Sun late in November, it has been up in the pre-dawn sky, creeping up higher each night.


It was observable in early December in New England, but very low in the sky before sunrise. I tried to get a look at it a few times using binoculars but was not able to see it well between the trees at home! Had hoped to see it later in December, but skies have been very cloudy and foggy for the past few weeks as part of a very unusually mild and damp weather pattern.


Having some time off recently, I thought I would try to see the comet using one of the internet telescope services available, and was able to get some images of it after signing up for a trial on slooh.com


After logging in and watching some of the getting started videos, I was able to book a timeslot (or “mission” as they call it) to see the Catalina comet on one of their telescopes in the Canary Islands . The site has a page titled “What’s Up” that gives a lot of great suggestions for currently observable objects to look at including planets, deep sky objects and visible comets. You simply select an available time, select the desired object you’d like to see and you are all set!


But for comets and other moving objects you need to determine the coordinates the target will be at and create a “Coordinate Mission” for that location of the sky. I used Stellarium to determine where Comet Catalina would be from the observatory location at the time of the reservation. Since the reservation times are in UTC, it is also handy to set the TimeZone plugin in Stellarium to work in that time zone. That way, you can check the position at a given time in UTC and not have to convert to your local time. (Or I guess you can change your workstation to UTC time and keep it there)! The coordinates calculated in Stellarium can be a bit off, so to get accurate positions expected from the coordinates of the actual observatory it’s good to use the MPC Minor Plan and Comet Ephemeris Service or the JPL Horizons site.


After you enter the coordinates, you select the type of object you are observing, so I selected the “bright comet” option. Apparently this setting determines the exposure time and image processing used for the session. The site appears to confirm that the coordinates are observable at the time selected and will even warn you if a fainter object is too close to the moon to be seen.


Once you set this all up, that’s it! You can stay on and watch the images from the telescope as they are taken. Since my reservation was around 1 AM local time, I just went to sleep while my images were being acquired!


The next day, I signed back into the site, selected the My Images page and found 4 images taken of the comet. The session used both a high magnification telescope (17″ CDK af f7) and a wide field APO refractor telescope. Images were taken at the same time, processed and made available as color and mono PNG files in the size of the original CCD images. These can be viewed on the site, downloaded, or annotated and emailed or shared to your favorite social media site.


Here is the high magnification image of C/2013 US 10 Catalina from this session on 30 Dec 2015:


20160108-01-catalina-2015-12-30-hm


It’s hard to see in the above version, but there is a faint tail extending up and right – I believe this is the dust tail. The ion tail extends a short ways down from the comet center. (North is up in this image).


I noticed several fuzzy objects around the comet. Not more comets, but apparently Catalina US10 was passing through an area with a few galaxies.


Slooh also provides FITS files from the CCD cameras. These are downloaded from the observatory at the end of each night and made available through the Slooh website and as well as an email notification.


So I was able to take the FITS file of the unfiltered or luminance image and reduce in Astrometrica. Then I could take estimated coordinates of each of the galaxies visible in the picture and check them against positions in TheSky. In the image above there are 5 clearly visible. I marked these in Astrometrica and they are shown in the image below, along with the fit and estimated location of the comets:


20160108-C2013-US10-SloohT2HM17


The dual tails are more clearly visible in the inverted image. I could also try stacking the color and luminance FITS files to see if I could bring these out better in the positive image. But I kind of prefer the above as it reminds me of working with AgBr imaging!


I took an image of the comet on the next night, and recently tried combining the FITS files to make my own LRGB composite using MaximDL. I need to better understand how to bring out the tails in that package but got a fairly good result:


20160108-C2013US10-2015-12-31-comb


The dust trail to the upper right appears to have a fork in it at this time – taken on 31 December.


The Catalina comet will continue to be visible through January and then fade as it moves away from the sun. Turns out this comet will not be back to greet us but will continue on outside of the solar system for parts unknown. Apparently is was a deep solar object that had its orbit perturbed enough to be knocked into an ejection trajectory that will take it outside of the Solar System.


Next, I will try capturing some of the other comets in the sky using Slooh and perhaps another similar service.