November - December Observing Report

Nov 19 2016

     First night out since the DSSG. A cold clear night with low humidity. At 9:23 pm it is 54 F with 55% humidity, dew point 38 F, breeze out of the NNE ~ 4 mph. I had the mount on the pier but I had to polar align the mount and then install the scope and other gear.  I setup with the 2” 0.75X FR + the MFR-3 and 1-1/4” Lumicon deep sky filter. Only the Baader 2” → 1-1/4” adapter in the optical train other than the 1” focuser ring. This should give me a field of 18.6 x 13.9 arcmin for a reduction of 0.613 and a F ratio of 4.91. Settings on the Mallincam are AGC 6, ATW, contrast 80 – 90, brightness 10 – 50% depending on object.  I continued working on the Herschel 400 list.

Herschel 17-6,  NGC 2158

Tracking and/or polar alignment is off as exposures > 30 seconds result in significant image shift and star trailing. Too tired to mess with drift alignment tonight. Shutting down at 1140. Sky meter reading = 18.95 .


Nov 25, 2016
A few high thin clouds tonight and 62 F,  83% humidity and no wind. Came out after 9 . My goal is to improve my polar alignment and then perhaps do a little viewing. Since I'm working mostly on polar alignment, I set up the Mallincam with no focal reducers at prime focus with an 1” focuser ring, an 80 mm extension tube, and a 2->1-1/4” adapter. No filters or focal reducers.

Went to Menkab in Cetus @ 2302 and centered the star with AGC dropped down to 2. 

 Iteratively tweaked the azimuth, re-centered the star,  and watched the drift.   After multiple adjustments I had it holding 5 minutes with the star is still dead center and approximately 1/3 the diameter down.Went to Procyon. It is a bit above the eastern horizon but I don't see any stars lower due to clouds that have built in form the East.  At 5 minutes there was no left/right drift evident only a down drift by ½ diameter. Locked down the azimuth locks. Went to Sirius, centered and started tracking.  At 5 minutes the star was still ½ diameter below the line but centered left to right.  That should have the alignment of the mount good enough for EAA observation.   I shut down for the night due to persistent clouds.

Nov 26, 2016

Came out a little after 8:00 on a cool night with temp around 49 and 88% humidity with no clouds in sight and no wind. Plan is to continue my Hercshel 400 hunt so I'll setup the Mallincam with the 2” FR + the MFR-8 for a reduction of 0.533 which has the scope operating at F 4.3. This gives me a FOV of 21.4 x 16.1 arcmin. I do have the 2” Lumicon deep sky filter installed. 

After fussing with my system for a bit, I finally came to the realization that the dust cap was still on!  Note to self: remove dust cap from scope before starting observing session.   I went on to hunt down a few Herschel objects until clouds rolled in around midnight.

 Shut down at 12:20.  Frustratingly I am still seeing some image shift. 

Dec. 9, 2016

A cold clear night with few clouds. Thankfully the wind has died down. At 2000 hrs it is 45 F with only 52% humidity, so dew shouldn't be an issue tonight. The moon however is near zenith and just past half so it will be an issue to the South.  I setup the Mallincam with the 2” 0.75x FR + the MFR-8 for a reduction of 0.533 which has the scope operating at F 4.3. This gives me a FOV of 21.4 x 16.1 arcmin. I'll use the 1/14” Lumicon deep sky filter tonight.

H317-2, NGC 2371-2372

At midnight a sky meter reading was 18.53 due to the > ½ moon high in the SW. The temp is still 44 F with 58% humidity.  I knocked out the Hershel objects in Gemini, Orion, and Canis major . I've now completed 30 objects on the Hershel 400. Shutdown ant 0109.  Frustrated that I'm still getting significant image shift after only 40 seconds or so. 

Dec 29, 2016

A front finally blew through and cleared out the skies, mostly. There are some high thin clouds around but the sky is pretty clear. Temp is 54 F and falling with light winds out of the North. The good news is the dew point is 36 F with only 52% humidity, so if the clouds will clear the transparency should be good. I setup with the 2” 0.75x FR + the MFR-8, with the 1-1/4” Lumicon DS filter.  The camera is setup with AGC=6, White balance = ATW, Gamma = 1.0, APC = 0,0, Cooling = off. Note I did not put the fans on the camera tonight.

At 0135 I took a sky meter reading of 18.74 . The temp is 49 F with a dew point of 35 and there is a slight N wind. No noticeable clouds since 10 pm. I knocked out some Herschel objects in Cassiopeia but it was getting pretty low so I moved up to Perseus and checked off all the objects in that constellation and then moved on to Auriga. I snagged 16 objects in total, a good night. I shut down at 0225 after a very productive night.

Focal Reduction

I respect visual astronomers and I understand the intimacy of having ancient photons from countless miles away hit your retina.  That works fine for bright stars, but but viewing faint grey fuzzies just isn't my thing.  I am active in astronomy because my Mallincam XT-418 ( upgraded Extreme II) allows me to see deep sky objects in greater detail and in color from my light polluted backyard.    

A challenge with using a video camera with a small chip is the small field of view (FOV).  On my VRC-10 (Focal length 2032 mm) and Mallincam XT-418 at prime focus provides a 14.24 arcmin FOV which is roughly equivalent to a 6 mm eyepiece.  This offers great magnification for small objects but the FOV is too small to capture many cosmic objects.  To obtain a larger FOV I could change to a shorter focal length scope, or change to a camera with a larger chip, or use a focal reducer - often called a telecompressor.   Another benefit of using a focal reducer is that it effectively reduces the focal length of the scope, thereby decreasing the F ratio and increasing the speed of the system.

I own several focal reducers, all sold by Mallincam; 

• MFR-6 (short half of the MFR-5) - an ~ 0.80 reducer,
• MFR-3 - an ~ 0.64 reducer,
• Mallincam 2" reducer - an ~ 0.75 reducer,
• MFR-8 (long half of the MFR-5) - an ~ 0.68 reducer, and
• MFR-5 - an ~ 0.44 reducer. 

These reducers can be used singularly or in many combinations.  To understand how best to employ these focal reducers, I've conducted experiments where I've measured the FOV with the plate solving website astrometry.net.   The software provides a solution of your image that includes the FOV size, as shown below.

The results from my experiments are shown below.  This data has been very helpful in planning observing sessions so I can match my optical system to the size of objects being viewed.    It also shows the required extension rings, tubes, and reducers and where the resulting focus point falls.  This greatly speeds up my setups.

Mallincam XT-418 Setups on VRC-10
Focal Reduction	1” Focuser Ring	Blue Fireball = 50 mm	Blue Fireball = 80 mm	Badder 2” - 1-1/4” adapter = 8 mm	Filter	Focus position	arcmin, horizontal	arcmin, vertical	diagonal dimension, arcmin	Calculated Reduction	Resulting F Ratio
prime Focus	x		x	x	Lumicon DS	25	11.4	8.54	14.24	1.000	8.00
MFR-6 (shrt hlf MFR-5)	x		x	x	Lumicon DS	26.5	13.1	9.85	16.39	0.869	6.95
MFR-3	x		x	x	Lumicon DS	24	14.2	10.6	17.72	0.804	6.43
MFR-8 (lng hlf MFR-5)	x		x	x	none	15.5	16	12	20.00	0.712	5.70
MFR-5	x	x		x	Lumicon DS	35	20.6	15.45	25.75	0.553	4.43
M 2” 0.75x	x			x	Lumicon DS	31.5	14.8	11.1	18.50	0.770	6.16
M 2” 0.75x + MFR-8	x			x	none	12.5	21.4	16.1	26.78	0.532	4.26
M 2” 0.75x + MFR-3	x			x	none		18.6	13.9	23.22	0.613	4.91

 
I experienced no comma or vignetting with any of the above systems, however I suspect that if I couple the 2" 0.75 reducer and the MFR-5 that I likely will see some vignetting.  My results are similar to those of others, although not exactly the same due to differences in the spacers used.   I plan several more experiments to try different spacers to alter the distance between the focal reducer lens and the camera chip.  NOTE: Additional experimental data on numerous focal reducers is available at Jim Thompson's  highly informative Abby Road Observatory website (look under Test Reports).

2016 Deep South Star Gaze, part II

Oct 27 - Third night of the DSSG
Heather came up after school so I had an observing buddy.  Set up the Mallincam with the 2” FC + the MFR-8, so I'll be running at F 4.26 with a FOV of 21.4 x 16.1 arcmin.   My observing plan is to continue with the Herschel 400 list I started last month.  At 2245 took a sky meter reading of 21.18 (6.22 mag). It is damp but clear and steady.

     At 0029 took another sky reading, and got 21.11. Has been a great night. I knocked out the 10 Herschel 400 objects in Cetus and saw a few other things as well.  I viewed a few objects through Heather's Edge HD-1100 and also I got to view the Orion nebula through a 25” Obsession dob.  Shut down at 0039.

Oct 28 - Fourth night of the DSSG
I decided to change my optical setup to the 2” FR + the MFR-3. Based on a astrometry.net measurement of an image of the ring nebula, this focal reduction combination provided a 18.6 x 13.9 arcmin field and F 4.91. I'm hoping this milder reduction setup will provide better color rendition.   I'm using the same settings on the Mallincam the past few nights, AGC 6, ATW, contrast 80 – 90, brightness 10 – 50% depending on object. After a view of the Ring Nebula, I continued my hunt of Hershal objects

At 2325 measured sky reading of 21.18 , a beautiful night.  I knocked out many objects in a really nice night although cold and damp. Shut down at 0158.

Oct 29
Fifth and final night of the DSSG. Same optical setup as last night. As I was viewing the first object of the evening, I bumped the mount (hit counter weight with my head – OUCH !!) I reset the scope to CWD position and cycled the GEMINI and cold started but my gotos were off.   The polar alignment was off so I obviously hit the counterweights hard.   I reset the polar alignment and built a Gemini model, but the stars in the Mallincam were not as bright as the past few nights.  I viewed a couple of objects and at 2324 I called it a night as I have to pack up and drive home tomorrow.  I frustrated my last night wasn't as good as the previous two, but I had 2 very good nights observing  I also won a couple of door prizes, including an Explore Scientific eyepiece.   We had a nice time at the DSSG.

2016 Deep South Star Gaze, part I

The 2016 Deep South Star Gaze, the 34th annual event, was memorable for the good attendance and weather. The days were warm with no rain and three of the five nights offered clear nights. This is always a nice, well run event  We had over 90 attendees and roughly 65 telescope setups.    The telescopes included small Dobsonians, a few large Dobs (including a 25"), several 8-12" Schmidt–Cassegrain and Ritchey–Chrétien, and quite a few refractors of various sizes.  Here are a few pictures from my walk around the field.

Some hardy folks camped out on the field and employed solar panels

to keep their batteries fully charged.

My tent and 10" RC riding a Losmandy G-11 on the right and my

daughter's Celestron Edge HD-1100 on the left.

Here on the Eastern side of the field you can see several scopes and on the far left

 of the image is 1 of the RVs.  The field has electrical hookups for upto 4 RVs, but

no water or sewer hookups.  

a closeup of my 10" Mallincam VRC on a G-11 mount

Oct 25 - First night of the DSSG
We arrived late in the afternoon.  The first order of business was to get the trailer setup and the air conditioner running as it was in the upper 80s.  Unlike previous years where I set up my scope on the Southeast side of the field, I picked a spot on the North side where the trees receded a way from the field.  Here I would have a view of Polaris to polar align the mount and better viewing to the South. By the time I had the tarp, tent, tripod, mount, and scope all setup, I was worn out. So I decided to just do some visual observing that night. I came out around 8 after eating a good supper.  Skies look reasonably clear but there are high thin clouds making the transparency poor. Humidity is not too bad, no star twinkle.

Polaris was surprisingly dim in the polar scope. After completing the setup of the scope I settled in to do some visual observing. Conditions were not conducive to seeing faint galaxies or nebula but star clusters were good. I was able to see the ring nebula although it was faint and the hole was not visible. NGC 457, the Double cluster, Andromeda Galaxy, were nice targets. I closed down for the night around midnight.

Oct 26 - Second night of the DSSG
The night started out with partially clear skies but the clouds soon filled the sky and the night was over by 9 pm.  I covered everything up and went back to the trailer and Cindy and I watched television.  Nice to have DirecTV in the trailer.   The weather forecast is for clearing skies for the next several nights.