Tuesday 30 December 2008

Clear skies continue!

The series of clear frosty skies is continuing here. Following my last report on December 22nd observations, I have been able to do more observations on the 26nd, 27th and 29th, plus a number of deep-sky guided astrophotography sessions.

But first the satellites. Captured targets on these nights were Lacrosses 3 & 4 (97-064A & 00-047A), the NOSS 3-4 rocket (07-027B), which is still slowly variable, and the NOSS 3-2 duo (01-040A & C).

The latter NOSS duo made a very nice pass across the Pleiades yesterday evening:

(click image to enlarge)

Yesterday, I slao shot this photograph of the open star cluster M35 in Gemini. It is a stack of 65 x 10s images, taken with the Canon EOS 450D piggyback on my Meade ETX-70. Lens was the same EF 50/2.5 (at F2.8) I use for the satellite imagery, and ISO was set at 1200.

(click image to enlarge)

Near the edge of the original, M1, the Crab Nebula, actually shows up as well:

(click image to enlarge)

I used an image of the Pleiades shot the evening of the 25th to glean some more indications of the astrometric positional accuracy of the EF 50/2.5 lens. The stacked image contains several asteroids up to mag. +12 (10 Hygiea, 21 Lutetia, 94 Aurora, 182 Elsa and 264 Libussa), and by measuring these in Astrometrica (highly accurate astrometric software I use for my asteroid searches in NEAT data) and comparing to the predicted positions, it turns out that the positional deviations are typically within 5" (that is arcseconds).

That is the same accuracy AstroRecord (the wide field astrometry software I use for my satellite images) indicates from the fit to the reference stars. So it is the timing uncertainty which is the main cause of uncertainty in my satellite positions.

Wednesday 24 December 2008

More on Monday evening

Below is a second astrophotography image I made last Monday evening (see previous post). It shows M31, the Andromeda Galaxy. The image is the result of stacking 100 images of 10s exposure each, made with my Canon EOS 450D + EF 50/2.5 Macro piggyback on my ETX-70.

(click image to enlarge)

Tuesday 23 December 2008

A very clear night, Lacrosses, the Breeze-M tank and the Pleiades

Yesterday evening (22 Dec) was very clear. I obtained photographs of the passes of the Lacrosse 5 rocket (05-016B), and Lacrosse 4 (00-047A)..

I photographed Lacrosse 4 with the Pleiades just before eclipse (see below). When inspecting the image for astrometric reduction, I noted a second, fainter trail on the image. Measuring it and running an ID, I found it was close to predicted positions for the Breeze-M (deb) tank, 05-019C. There was an odd 0.6 degree discrepancy though. Mike solved it by pointing out that a SDP4 solution yielded perfect residues, while the SGP4 theory SatFit uses doesn't. So, the question mark plus the "UNID" in below image can be erased.

(click image to enlarge)

Later that night, after the LEO window closed, I spent some time doing astrophotography with my camera piggyback on my Meade ETX-70. I still have to stack part of the images, but already finished stacking 102 x 10s exposures of the Pleiades with the EF 50/2.5 lens, yielding this result:

(click image to enlarge)

Monday 15 December 2008

Short observing session

Saturday evening saw a short break in the bad weather, and some clear sky. A slight haze and near full moon made the conditions not too excellent, but I managed to catch positions on Lacrosse 5 (05-016A) and the NOSS 3-2 duo (03-054A & C).

Below is a picture of the latter crossing near Polaris.

(click image to enlarge)

Wednesday 10 December 2008

Bad weather

Bad weather and midwinter situations leading to only a very short observation window right after dusk are the main reasons why observing has come to a stop at the moment. I haven't been able to observe since November 29th, which itself was preceded by a period of forced non-observation due to the weather.

This means I spent some time hunting asteroids again in archive imagery of the NEAT project. It was (and is) a rather prolific stint of asteroid hunting, yielding the following new designations (with a few datasets still pending):

tmp. desig.
2002 PN188
2002 WQ27
2001 SD355
2002 WR27
2002 XK118
2002 UU76
2002 WV27
2002 WW27
2002 WX27

For a complete list of my discoveries, see here.

Two of the new discoveries (2001 SD355 and 2002 WV27) are Jovian Trojans moving in the L4 and L5 Lagrange points of Jupiter, 60 degrees on either side of it, sharing the planet's orbit. It are my first trojan discoveries.

In total I now discovered one Near Earth Asteroid (in the Spacewatch FMO program) and (in the NEAT archives) two Trojans and 22 main belt asteroids.