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Another B 33 Thread

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#1 Patricko

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Posted 13 January 2013 - 04:04 PM

Hello everyone,

Hope everyone is well. Last night I tried to see this object for the first time making a serious attempt.


Jan. 12th 2013

Time: 8:45pm-10:35pm

Location: Lat:32.9 Long: -105.9 Alt: ~1,433m

Conditions: cold (30 degrees F starting 22 degrees F ending), no Moon, light
breeze then calm.

Transparency: 7/10 starting - 8/10 ending

Seeing: varied from 2/5 to 3/5

NELM: 5.7m

Instrument: 4.5" Starblast (real measurements 109mm X 458mm @ f/4.2)


Notes: Went to find B 33 and IC 434. No luck and part of it could be I was not looking in the exact correct location. NGC 2023 was visible and I was seeing stars into the 12.5m to 12.7m range with averted vision. Even though I was off by 1/4 of a degree when centering the eyepiece I still did not detect IC 434 or B 33 with any amount of effort. I tried averted vision, deep breaths, and tapping the scope. I do not own a filter or that would have also been tried.

Eyepieces utilized in this attempt were:

26mm Meade 4000 Series 4-element "Super-Plossl" ----6.1mm exit pupil
25.1mm Sterling 4-element ----6.0mm exit pupil
17mm Sterling 4-element ----4.0mm exit pupil
12.5mm Sterling 4-element ----3.0mm exit pupil
12.4mm Meade 4000 Series 4-element "Super-Plossl" ----2.9mm exit pupil
9mm Orion Expanse 5-element ----2.1mm exit pupil
6.4mm Meade 4000 Series 4-element "Super-Plossl" ----1.5mm exit pupil

2.5x 3-element Barlow Lens was also used with:
12.4mm Meade 4000 Series 4-element "Super-Plossl" ----1.2mm exit pupil
6.4mm Meade 4000 Series 4-element "Super-Plossl" ----0.6mm exit pupil

Some thoughts I have on this target... Alnitak is blindingly bright so getting it out of the FOV is probably the best way to detect IC 434 and B 33. NGC 2023 is downright easy as is NGC 2024. My C6 SCT has a much more narrow FOV than this fast reflector so perhaps I would have a better chance using it; not so much for the added aperture but for the smaller FOV.

Some questions to those who might know...

1. Do you need a filter to detect B 33 and IC 434?

2. I've seen IC 434 before in small scopes but it looked like a very faint
elongated smokey mist with no defined shape. Am I missing something here or shouldn't B33 be detectable at this point?

3. What exit pupil and/or magnification did you use to see these objects?

4. Has anyone seen this object and sketched it using a 60mm-150mm telescope and/or binoculars? If not, what is the smallest aperture with which these objects have been detected?

5. Is this just downright impossible with such a small scope from a town with ~40,000 people without a filter?

What I have learned:

I have a whole set of Sterling Plossls. I bought them for detection of faint DSOs based on the recommendation of many CloudyNights members. I am not disappointed with any of them except the 4mm which came with dirt inside the lens assembly. The Sterlings have wider FOVs and require more in-focus travel than my Meade 4000 series "Super-Plossls"; however, after nearly 2 hours of comparing views where faint targets are concerned I have learned that my Meade 4000s not only keep up with the Sterlings on faint targets but actually reveal the absolute FAINTEST stars easier consistently!

I really am unable to explain this yet it is what it is.
Any ideas as to why? Most of my Meade 4000s are the JAPAN 4-element versions if that matters. Faint stars engulfed in nebula which make for low contrast targets show the greatest noticeable differences between the two eyepiece lines. Star colors and background seem to be nose-to-nose. The newt was collimated and cooled before I started my session and my right eye was dark adapted while switching back and forth between the different eyepieces. I will say the rubber eye guards are very nice to have when keeping exterior lights at bay.

For many years I have often thought of bagging B 33 and last night was the first time I really gave it any effort. Hopefully some other observers more experienced may have some ideas to offer. Thank for any help!

#2 GlennLeDrew

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Posted 13 January 2013 - 07:28 PM

The smallest instrument I've bagged B33 with was a 120mm refractor, using a UHC filter.

At smaller apertures filtering is important, so as to boost the contrast of the small dark cloud. As aperture increases, one enjoys increased magnification while retaining a large exit pupil, and so detection becomes possible without contrast-boosting filtration.

I've seen B33 relatively easily through a 16" without a filter, and with a not-too-far-from-first quarter Moon above the horizon.

#3 blb

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Posted 14 January 2013 - 10:37 AM

Some questions to those who might know...

1. Do you need a filter to detect B 33 and IC 434?

2. I've seen IC 434 before in small scopes but it looked like a very faint elongated smokey mist with no defined shape. Am I missing something here or shouldn't B33 be detectable at this point?

3. What exit pupil and/or magnification did you use to see these objects?

4. Has anyone seen this object and sketched it using a 60mm-150mm telescope and/or binoculars? If not, what is the smallest aperture with which these objects have been detected?

5. Is this just downright impossible with such a small scope from a town with ~40,000 people without a filter?


1. No, but a filter will help you see the nebula IC 434. The Horsehead, B33, is a dark nebula and therefore is the absence of the nebulas light. What you see is a dark place, B33, in the faint nebula.
2. Yes, the nebula is a very faint hazy spot. The eastern edge is easiest to see and this is where you will find the Horsehead. There are many good star charts on the web that will help you find the exact location of B33. Print one and use it at the scope. You may find that without a filter that it is only visible with averted vision.
3. Check out this site for exit pupil size, http://home.ix.netco...b/MEyepiece.htm
4. Yes, I have seen it with my TV102 refractor from a dark sky site in the mountains of western North Carolina. The NELM was 6.2 to 6.3
5. I don't know. Light pollution will make it much harder to see the nebula without a filter. Remember you can't see B33, what your looking for is the absence of the nebula so you have to see the nebula to make out the Horsehead.

Another good source of information on seeing the Horsehead can be found in this web site;
http://web.archive.o...ro-app/horse...
and here:
http://freescruz.com...ro/HH-sense.htm

#4 David Knisely

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Posted 14 January 2013 - 05:12 PM

The Horsehead can be one of the more difficult objects to see, especially in smaller scopes. While it can sometimes be seen under good conditions without a filter in moderate to large apertures, the H-Beta filter is usually key to making it more easily seen. The smallest scope I have seen it in is a 100 mm aperture f/6 refractor at 25x using the Lumicon H-Beta filter, but it was quite marginal in appearance. It appeared as a rather vague notch in an already incredibly dim glowing background that was glimpsed only with averted vision and was scarcely brighter than the regular night sky glow. In fact, had I not known exactly where it was in relation to the stars in and around the nebula, I probably would not have noticed it. It takes fairly dark skies, a little aperture, and lots of experience to observe it. Once you see it, you should be able to more easily repeat your sightings on other nights, as a lot of seeing it is knowing what to look for. Good luck and clear skies to you.

#5 Patricko

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Posted 14 January 2013 - 06:55 PM

Hello everyone,
Here are my notes from last night:

Date: 1-13-13
Time: 7:45-8:50pm
Location: My backyard
Conditions: cold, ~30-28 degrees F, started mostly cloudy with high clouds breaking way with clear skies after ~10mins.
Seeing: 2/5 except at zenith 3/5
Transparency: 5/10 beginning : 8/10 ending
NELM: 5.7
Instrument: C6 SCT 2011 XLT Model

Observed:

IC 434 & B33- extremely difficult and faint! First glimpse with 17mm Sterling Plossl at ~94x with a 1.59mm exit pupil. This gave a FOV of .56 degrees. HIP 26816 and NGC 2023 were placed just outside of the FOV in order to enhance sky darkness. Deep breaths, averted vision, and scope jiggling were used to catch the contrast differences in detecting the southern boundary of the Horsehead Nebula. More concentration was necessary to detect the western and northern boundary of B 33.

I started with a 32mm Meade 4000 SP, and then switched to a 26mm Meade 4000 SP. No luck in detecting any background shade variations and the 32mm made keeping Alnitak out of the FOV Impossible. The FOV displayed an arc of light induced by the C6 SCTs internal baffle, this really hurt contrast across the FOV making it almost impossible to see anything faint. This occurred when Alnitak was placed just outside the FOV or on the field stop of the eyepiece. A 20mm Sterling was then used to scan the same area. Hints of IC 434 became visible just west of the 11th and 12 mag stars which I later discovered are just south of B 33. Finally I used the 17mm Sterling, it was this eyepiece that was used to detect B 33 for the first time. It was appearing ~20% of the time as a darkening indentation obstructing into IC 434. I then was able to go back thru the previous eyepieces and see it in them; the 32mm Meade 4000 SP was the hardest eyepiece in which to see B 33.

When examining NGC 2023 further I noted asymmetry in the nebula around HIP 26816. The NW portion abruptly cuts thru an otherwise fairly perfect circle. With averted vision in the 17mm this nebula almost displays a spiral shape. Excitement of seeing B 33 swayed my attention from trying higher powers.

After trying for over 30 minutes to successfully observe B 33, NCC 2024 was extremely bright and easy. I even think to have observed nebulosity around HIP 26742 about 1/2 degree NNE of Alnitak. Stars in the 14th mag range were detected around IC 434 and B 33 with the 17mm Sterling. Knowing almost exactly where to look (thank goodness for star charts) this object might be impossible to find under similar sky conditions using a 6” scope. I wonder how much easier a filter would have made detecting B 33, if I ever get a filter I will find out.

Being able to observe successfully this dark nebula from within a small town of 40,000 people makes me ecstatic! I would place B 33 in the same category of difficulty with detecting the outer shell (not the bright inner shell) of PN NGC 6826 (The Blinking PN) with the C6 SCT under darker skies.

Below is a photo of my crude sketch from memory of IC 434 & B 33. I sketched it immediately after coming in from observing the object. I feel it is accurate as I studied it carefully once found for over 30 minutes.

Many thanks to Buddy, Glenn, and David for sharing good information.

Attached Files



#6 GlennLeDrew

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Posted 14 January 2013 - 10:26 PM

Patrick,
Your sketch suggests what is already well known. And that is, where a sharper discontinuity in surface brightness exists is where detection is rather more likely. That is, a 'sharp' edge is easier to see than a diffuse fading.






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