Tuesday, March 19, 2013

Siamese Twins Galaxies

Siamese Twins Galaxies by S Migol
Siamese Twins Galaxies, a photo by S Migol on Flickr.
Via Flickr:
The Siamese Twins Galaxies, NGC 4567 and NGC 4568.

These two galaxies are part of the Virgo cluster and are about 60 million light years distant.

Taken over a series of three nights at home. I only used two nights of data as the third night was so far off center and it only had an hour's worth of subs that it wasn't worth using.

Taken with the modified Pentax K10D camera running at an EXIF temp of 9-11C (TEC set to -5C). Used the Orion 127mm Maksutov Cassegrain scope. Tracking was hard to nail down over the sessions as the air turbulence was making a challenge. I had a struggle keeping the RMS at 1 arcsecond, which was above the resolution of this setup. Thus, all details are blurred. I think that much of this lies at the use of the Orion ST80 as a guide scope with a poor quality IR filter. The guide star images didn't have good centroids.

Guided and calibrated with Maxim using 12 darks, 64 bias, and 16 flats and hot pixel map.
Registered and Stacked using PI as DSS couldn't detect the faint stars remaining after calibration.
Rest of the processing in PI used masked stretch, DBE, A trous wavelet processing (including a large scale flattening effort to smooth out some odd rings).

There is a fair amount of detail, but this is limited because of the guiding issues. I'm not sure that I'll have a chance to return to this target before the end of the month.

The reason why I selected this target was because I'd "won" the Cloudy Nights competion with the Jellyfish Nebula picture from two months ago. I thought that all the SCT owners would jump at the chance to image something like this target.

Here's the PI-generated plate solve:
Referentiation Matrix (Gnomonic projection = Matrix * Coords[x,y]):
+0.000000503647 +0.000228108926 -0.246675434483
-0.000228060582 +0.000000327102 +0.349607831977
+0.000000000000 +0.000000000000 +1.000000000000
Resolution ........ 0.821 arcsec/pix
Rotation .......... -90.110 deg
Focal ............. 1524.81 mm
Pixel size ........ 6.07 um
Field of view ..... 41' 60.0" x 29' 30.3"
Image center ...... RA: 12 36 36.612 Dec: +11 14 02.27
Image bounds:
top-left ....... RA: 12 35 36.181 Dec: +11 35 00.44
top-right ...... RA: 12 35 36.705 Dec: +10 53 00.80
bottom-left .... RA: 12 37 36.664 Dec: +11 35 02.99
bottom-right ... RA: 12 37 36.897 Dec: +10 53 03.33