Caldwell 45 (NGC 5248) (Stephen Migol)

Caldwell 45 (NGC 5248)

Caldwell 45 or NGC 5248 is in the constellation Boötes and was a good target to test for setup in the backyard. The clear skies lasted two nights and were enough to confirm that the problems with flexure are under control.

This constellation is a small, 10th magnitude spiral galaxy. In larger instruments it shows nicely. In my 4 inch scope, it's barely visible through the background skyglow and light pollution.

Standard setup: Stellarvue SV4 scope, modified and cooled Pentax K10D camera. SSF6 flattener, IDAS LPS D1 filter. 28 - 1200 second subs stacked for 9 hours of integration.

Calibrated with Maxim, Stacked in DSS, Processed in PI.

My process in PI was to crop, DBE (2x), Masked Stretch, Luminance mask made from Range Selection tool, mask applied to darken the background and lighten the foreground with curves. Note that I did not do any PI noise reduction on the image aside from the original calibration.

Once exported to TIFF and passed through LR 5, I did give a touch (5) of NR for luminance and chrominance. This helped smooth the worst pixels of the background.

Here's the platesolve results from PI:

Referentiation Matrix (Gnomonic projection = Matrix * Coords[x,y]):

-2.25736e-006 -0.000530442 +0.642983

+0.000530332 -2.36642e-006 -0.957197

+0 +0 +1

Projection origin.. [1810.277785 1204.460670]pix -> [RA:+13 37 36.82 Dec:+08 55 03.20]

Resolution ........ 1.909 arcsec/pix

Rotation .......... 89.744 deg

Focal ............. 653.55 mm

Pixel size ........ 6.05 um

Field of view ..... 1d 55' 14.0" x 1d 16' 39.8"

Image center ...... RA: 13 37 36.813 Dec: +08 55 03.62

Image bounds:

top-left ....... RA: 13 40 12.607 Dec: +07 57 35.79

top-right ...... RA: 13 40 11.438 Dec: +09 52 47.95

bottom-left .... RA: 13 35 03.002 Dec: +07 57 15.32

bottom-right ... RA: 13 35 00.200 Dec: +09 52 27.38

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Status	Advanced success
Started	...
Astrometry.net job	6595488
PixInsight job	LQLHD68BL5JT56FVZDVIAY7HKRPLOZR0
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	13h37m36s.77
RA (top/left)	13h40m12s.32
RA (top/right)	13h40m11s.57
RA (bottom/right)	13h34m59s.99
RA (bottom/left)	13h35m02s.83

Dec (center)	+08°55′02″.3
Dec (top/left)	+07°57′38″.3
Dec (top/right)	+09°52′52″.6
Dec (bottom/right)	+09°52′24″.4
Dec (bottom/left)	+07°57′21″.3

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