SAC Abell 1656 - the Coma Cluster - is a collection of hundreds of galaxies in the apparent direction of the constellation Coma Berenices. The cluster is rich and fills the field of this image. Brightest members of the galaxy are centered in the view and Are mostly 12th magnitude. Review the annotated versions to get an idea of the large amount of potential objects in this field.
Flickr:
https://flic.kr/p/neDvEiNGC Annotated on Flickr:
https://flic.kr/p/nu6s9JPGC Annotated on Flickr:
https://flic.kr/p/neDtnTTaken over two nights at Montebello Open Space preserve. Both nights suffered from transparency issues with high clouds coming and going. As I haven't had a chance to return to the site, I wanted to get this data processed.
19 subs used at 1200 seconds each for a total of 6 hours and 20 minutes of integration. Used the IDAS HEUIB filter vs the LPS filter I normally use. I thought that the dim area would benefit from less light pollution control.
Flats were taken with the dew shield in place. Taking flats without the dew shield led to over-correction of the edges.
Calibrated with Maxim with two sets, one for each night as the ambient temperature was different. May not have needed to do this step as just one set of flats was used.
Stacked in DSS. Had some issues with airplane trails not getting removed with median sigma clipping. In the end, I needed to drop the sub.
Processed in PixInsight with these steps: Crop, DBE, Color Calibration, Curves Saturation boost while linear, Masked Stretch script, Histogram Stretch to reset black levels, Masked Unsharp, Masked curves to boost RGB/K values. No noise reduction was needed after calibration. Nice to work with a cold camera!
While I'd like to return to this target again, I want to explore other techniques to prepare for GSSP 2014.
Here's the platesolve from PixInsight:
Referentiation Matrix (Gnomonic projection = Matrix * Coords[x,y]):
-4.73824e-006 -0.000530581 +0.671293
+0.000530349 -4.85691e-006 -0.926158
+0 +0 +1
Projection origin.. [1757.760819 1249.506462]pix -> [RA:+12 59 47.38 Dec:+27 57 47.53]
Resolution ........ 1.910 arcsec/pix
Rotation .......... 89.469 deg
Focal ............. 653.47 mm
Pixel size ........ 6.05 um
Field of view ..... 1d 51' 54.3" x 1d 19' 32.2"
Image center ...... RA: 12 59 47.384 Dec: +27 57 47.99
Image bounds:
top-left ....... RA: 13 02 48.228 Dec: +27 02 06.43
top-right ...... RA: 13 02 46.814 Dec: +28 53 58.58
bottom-left .... RA: 12 56 51.048 Dec: +27 01 23.11
bottom-right ... RA: 12 56 43.410 Dec: +28 53 14.52
Comments