Thursday, February 27, 2014

Monkey Head Nebula

Monkey Head Nebula Monkey Head Nebula (NGC 2175)

This is the product of some work over this winter, starting with a few subs at Calstar 2013 and continuing into January and February 2014.

Challenge with this target was the flare from the nearby star Propus. It causes an orange glare across the field, centered on a corner of the image, depending on which side of the meridian the camera is positioned. I've added some more flocking to the flattener. As I am unable to disassemble the flattener, I'll be experimenting with "lens hood" designs to eliminate the off-axis glare.

Normal configuration for my digital astrophotos: Stellarvue SV4 with the SSF6 flattener. What varied was the use of the filters in place.

At Calstar, 4 subs were just using the B+W 486 UV/IR filter.
At Montebello OSP on Jan 31, a stack using the IDAS HEUIB II filter with the IDAS LPS P2 filter.
At Montebello OSP on Feb 24, a stack using just the IDAS LPS D1 filter.

Used a total of 32 subs for 10 hours 42 minutes of integration. 1200 second subs.

Camera temperature was run wide open. Ambient temperatures varied - at Calstar, the temps were just above freezing. At MBOSP, the ambient temps were about 50 F. In both cases, I was able to use camera darks in the 7-10C range.

Calibrated using Maxim with a library of darks, bias, and flats from each night.

Stacked in DSS.

Processed in PixInsight. Steps used were crop, DBE, masked stretch, histogram stretch to set black point, masked MT, then unmasked curves to reset black point and boost saturation, masked unsharp mask to boost sharpness on the brightest features.

I did not use the noise control features of PI because the data was very clean.

Referentiation Matrix (Gnomonic projection = Matrix * Coords[x,y]):
+3.76138e-005 -0.000529254 +0.555137
+0.000529155 +3.77391e-005 -0.972138
+0 +0 +1
Projection origin.. [1753.455798 1173.523067]pix -> [RA:+06 09 30.54 Dec:+20 35 01.59]
Resolution ........ 1.910 arcsec/pix
Rotation .......... 94.066 deg
Focal ............. 653.37 mm
Pixel size ........ 6.05 um
Field of view ..... 1d 51' 38.2" x 1d 14' 42.7"
Image center ...... RA: 06 09 30.544 Dec: +20 35 01.67
Image bounds:
top-left ....... RA: 06 11 51.953 Dec: +19 36 38.78
top-right ...... RA: 06 12 27.693 Dec: +21 27 56.50
bottom-left .... RA: 06 06 35.434 Dec: +19 41 55.70
bottom-right ... RA: 06 07 07.321 Dec: +21 33 17.29