The discovery of asteroid 2013 GM21

I am way behind with my reporting on this blog, for which I apologize. I still have satellite observations from early March to report, as well as (somewhat off-topic) observations of comet 2011 L4 PANSTARRS and spectacular Aurora borealis (Northern Lights) from Finland mid March. For various reasons, I did not come to that yet. Maybe coming weekend...

Meanwhile, a short report on my latest asteroid discovery: 2013 GM21, which was published in the DOU MPEC K13-G54 today (Apr 12, 2013: look for object K13G21M).

On  April 6th, I was on my own initiative (and successfully) trying to get follow-up observations on three objects (2013 EZ102, 2013 EB103 and 2013 EC103) which Krisztian Sarneczky and I discovered in the Konkoly survey from MPC 461 (the 60-cm Schmidt of Konkoly, HU) mid-March. I was "remotely" using the 81-cm Schulman telescope of the Mt. Lemon Sky Center (MPC G84) for that, one of the telescopes in the SSO Network.

In the images that should (and did) contain 2013 EZ102, I found two other moving objects. Both were unidentified - i.e., they were not in the MPCOrb asteroid database of the IAU Minor Planet Center and could be new discoveries! So they were submitted to the MPC with the temporary designations LaMa515 and LaMa516.

One of these (LaMa515) turned out to have been observed by another observatory just days before, so that one was not a new discovery: the other observatory alas beat me to it.

click image to enlarge

The second object however, a mag +19.5 to +20 object I temporarily designated LaMa516 moving quite close to 2013 EZ102 in the images, turned out to be truely new: my observations of April 6th were the first! It can be seen in the blink above, which shows you a small part of the April 6th discovery images. 2013 EZ102 is in the images too.

I next obtained new images, based on a very rough search orbit fit, on April 7th, 8th and on April 11th, again using the 81-cm telescope of MPC G84. As a result, it was formally MPEC-ed today by the MPC as 2013 GM21: my second asteroid discovery using a "remote" telescope! And my 69th asteroid discovery in total (and 5th in 2013, the other four being in the Konkoly survey. For a full list of my discoveries see here).

The asteroid is a borderline Maria family main belt asteroid. With H=16.8, it is an estimated 1.5 km large. It has the following orbital elements (source: MPC):

2013 GM21

Epoch 2013 Mar. 29.0 TT = JDT 2456380.5   MPC
M 351.06235              (2000.0) 

n   0.24233744     Peri.   39.90632             
a   2.5479390      Node   164.25356             
e   0.0734092      Incl.   17.12483

q   2.3608968      T       2456417.38101 JDT 

P   4.07           H   16.8 

From 13 observations 2013 Apr. 6-11.

click images to enlarge

As can be seen in the orbital plots, the orbit is well inclined to the ecliptic. I discovered it when it was in opposition and close to perihelion of its orbit, these two factors combining in a maximum brightness for the object. This is basically the same situation as with my earlier discovery 2012 SM58.

A farewell view of Space Shuttle Discovery

This evening in twilight (sun at -8 degrees altitude) we had a last pass of the "dynamic duo" Space Shuttle Discovery STS-133 and the International Space Station (ISS).

After it's landing tomorrow late afternoon, Discovery will be retired.

The two were well visible in a still bright blue sky, with Orion just visible. They sailed under Orion through Lepus, the Shuttle leading 37.4 seconds (about 19 degrees at culmination) in front of the ISS.

Below is one of the images I shot, using the EF 2.8/24mm lens at 4 second exposure, 200 ISO. The Shuttle is the trail on the left, ISS on the right:

click image to enlarge

Several other European observers reported a water-dump, visible as a "comet tail" behind the Shuttle. I didn't see it from Leiden though, likely because the sky was still too bright.

Space Shuttle Discovery STS-128

Yesterday it was a close call whether I would see the Space Shuttle Discovery STS-128 or not. A large field of clouds passed in late twilight, and only moved away some 10 minutes before the Shuttle pass. The clouds made me miss the newly launched Japanese HTV cargo ship to the ISS.

But the clouds moved away in time, and there it was: about mag. +2 to +2.5 and fast, and...39 seconds early on predictions based on orbital elements of earlier that day.

Three minutes later, the ISS sailed by in its majestic fashion.

The image below shows the shuttle passing through Ophiuchus.

click image to enlarge

Magnificent view of Shuttle and ISS just before docking!

I had a pass of the Space Shuttle Discovery STS-119 and the ISS this evening about one hour before they docked. This meant they were moving as a very close pair. The pass was around 19:10 UTC at 25 degrees altitude.

It was a beautiful sight, as the pair rose in the southwest and then majestically sailed past Sirius. Here's a picture:

(click image to enlarge)

The Shuttle is the object slightly fainter and lower in the sky. Movement is from right to left. Here's a second picture:

(click image to enlarge)