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

Tuesday, February 25, 2014

Chasing Internal Reflections

Propus Flare is Giving Grief

I've been working on the Monkey Head nebula for a little while and have noticed a consistent challenge of flare from Propus casting a gradient and reflection rings across the field.

I first noticed this issue at Calstar.  I figured then that it would be less of an issue once I gathered more subs.


Note that during the Calstar example as seen above, the only filter used was the B+W 486 UV/IR. Note the orange flare across the frame from the lower left upwards. Also notice the two rings at the corner.

Friday, February 14, 2014

Cephus to Cassiopeia on E200

Cephus to Cassiopeia on E200 by S Migol
Cephus to Cassiopeia on E200, a photo by S Migol on Flickr.
Via Flickr:
A widefield image taken at Calstar 2013.

The field spans from Cephus to Cassiopeia with north to the right, West to the bottom, and East to the top of the frame. The bright nebulosity pattern on the upper right is Sh2 171. The cluster of nebulosity in the center of the field is the Bubble Nebula. The yellow/orange star at the bottom of the frame is Zeta Cephei.

Shot on Kodak Ektachrome 200 120 film with a Pentax 67 camera with the SMC Pentax 6X7 165mm f/2.8 lens at F4. 60 minute exposure pushed one stop in processing. Scanned with Epson V700 and curves in LR5.

Wednesday, February 12, 2014

Perseus to Taurus on E200

Perseus to Taurus on E200 by S Migol
Perseus to Taurus on E200, a photo by S Migol on Flickr.
Via Flickr:
A widefield image taken at Calstar 2013. In the frame are the California Nebula and the Pleiades. Also seen crossing the frame are filaments of the molecular cloud in Perseus.

Shot on Kodak Ektachrome 200 120 film with a Pentax 67 camera with the SMC Pentax 6X7 165mm f/2.8 lens at F4. 60 minute exposure pushed one stop in processing. Scanned with Epson V700 and curves in LR5.

It's pretty obvious that shooting this lens at F4 leaves a lot of vignette still visible. I passed the file through LR5 to try to control the edges. Still, the color shift is noticeable at the corners and I've left intact to remind what it can show.

There are some additional strange artifacts that appear across several of the images as horizontal bands. These might be reflected light from car headlights or even light shining off the telescope tube. Or they could be scanning artifacts.

Gemini to Orion on E200

Gemini to Orion on E200 by S Migol
Gemini to Orion on E200, a photo by S Migol on Flickr.

Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way and large nebulosity at the feet of the twins of Gemini towards Orion. The frame is centered on the Monkey Head nebula. Also seen are Jellyfish nebula. The two large areas of reddish glow are Sh2 264 and Sh2 273.

Shot on Kodak Ektachrome 200 120 film with a Pentax 67 camera with the SMC Pentax 6X7 165mm f/2.8 lens at F4. 60 minute exposure pushed one stop in processing. Scanned with Epson V700 and curves in LR5.

Monday, February 10, 2014

Gemini to Taurus on Acros

Gemini to Taurus on Acros by S Migol
Gemini to Taurus on Acros, a photo by S Migol on Flickr.

Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way from Gemini to Taurus between Orion and Auriga.

The field is centered on IC 2159 or the Monkey Head Nebula. This cloud of glowing gas was recorded on the film, a surprise considering the relative insensitivity of the film to Ha. Compare it with the Jellyfish Nebula near Propus. The latter nebula is nearly invisible. Also visible are several open clusters including M35.

Shot on Acros 120 film with a Pentax 67 camera using the 165 mm lens at F4. 40 minute exposure - as all the Acros at Calstar was this duration. Scanned with Epson V700 and curves in LR5.

Friday, February 7, 2014

Auriga widefield on Acros

Auriga widefield on Acros by S Migol
Auriga widefield on Acros, a photo by S Migol on Flickr.

Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way. Several open clusters step higher in the frame.

I was finally able to identify the starfield as Auriga after having it platesolved at Astrobin. It is centered on the nebulosity around M38 and IC 410. The whole field starts with M35 in the lower left and the diagonal line going up from right to left shows M37, M36, and M38. In the upper right corner are Barnard 15, 16, and 17. The nebulosity slightly south and right of center is IC 417. The brightest star at the top is Capella.

Shot on Acros 120 film with a Pentax 67 camera using the 165 mm lens at F4. 40 minute exposure - as all the Acros at Calstar was this duration. Scanned with Epson V700 and curves in LR5.

Tuesday, February 4, 2014

Milky Way Clouds on Acros

Milky Way Clouds on Acros by S Migol
Milky Way Clouds on Acros, a photo by S Migol on Flickr.

Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way in Cygnus. The Veil and North America nebula are plainly visible if you know where to look. I'm surprised that these nebulosities show up given the use of the yellow filter.

The focus is not precise on this shot, there's noticeable softness in the center. This is an old design 200mm lens which may be the biggest problem. Next time I'm shooting film, I'll take a note of focus positions and see if I can pick up a copy of the modern 200mm lens.

Shot on Acros 120 film with a Pentax 67 camera using the S-M-C Takumar 6X7 200mm f/4 lens at F5.6 with a Y2 filter to increase contrast. 40 minute exposure. Scanned with Epson V700 and curves in LR5.

Milky Way Clouds on Acros

Milky Way Clouds on Acros by S Migol
Milky Way Clouds on Acros, a photo by S Migol on Flickr.
Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way from Aquila to Sagitta. The Triple Cave nebula is centered in the frame as I was taking a digital image at the same time.

Shot on Acros 120 film with a Pentax 67 camera usign the SMC Pentax 6X7 165mm f/2.8 lens at F4 with a Y2 filter to increase contrast. 40 minute exposure. Scanned with Epson V700 and curves in LR5.

Monday, February 3, 2014

Milky Way Clouds on Acros

Milky Way Clouds on Acros by S Migol
Milky Way Clouds on Acros, a photo by S Migol on Flickr.
Via Flickr:
A widefield image taken at Calstar 2013 showing the dark clouds of the Milky Way from Aquila to Lyra. The Triple Cave nebula and M27 are visible as well as many of the dark lanes in this part of the sky.

Shot on Acros 120 film with a Pentax 67 camera using the SMC Pentax 6X7 165mm f/2.8 lens at F4 with a Y2 filter to increase contrast. 40 minute exposure - don't remember if there was a push. Scanned with Epson V700 and curves in LR5.

There is a gradient from south to north that comes from the glow on the horizon. I could fix it a little, but I'm not sure that this is all a problem.

Note the lens flare near the top of the image from Vega.