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Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle
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Sh2-101 (Tulip Nebula) to NGC 6883. A First Light Project on a Travel Rig

Revision title: As per Discussion, new pre-processing solved the donut stars and made other stuff better.

Getting plate-solving status, please wait...
Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle
Powered byPixInsight

Sh2-101 (Tulip Nebula) to NGC 6883. A First Light Project on a Travel Rig

Revision title: As per Discussion, new pre-processing solved the donut stars and made other stuff better.

Equipment

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Acquisition details

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Description

This is a first light image from a new travel rig that I have put together in the last couple of weeks.  The justification to do this project (aside from the fact that I live in an area that has horrible prospects for regular imaging) is that my family and I will be going on a vacation to the Rocky Mountain National Park area.  The wife and kids will fly, but I decided to drive.  As it was, I had purchased a William Optics ZS61 II last year to use as a guide scope for my larger rigs, though it was always in the back of my mind that I would potentially use it for other purposes as well.  In any case, after the vacation, I will take a detour and head down to the dark country of south central, west New Mexico and spend a week in a rental cabin.  Bortle 1 area at ~8k ft.  Hopefully I don't hit the worst of the monsoon season.  At this time, the moon will be out of the way.  My trip there is to rekindle efforts to find a place that can serve as a second home/cabin and observatory.  My wife and I had been to the locale before and like it, even if it is rather remote.  (Just over the border in AZ is also within my sights.)  Below is a list of the components, most of which are pictured in revision B:

1. WO ZS61 II.  61mm, 360 mm f.l.  Field flattener. Rotator and filter slider w L-pro.  (Should have a UV/IR cut filter, but the L-pro will work.)
2. ZWO AM5 mount with lightweight, short carbon fiber tripod.  
3. ZWO ASI071 MC pro.  Admittedly, not a great match pixel-wise for the scope, no matter which seeing conditions, certainly not the Bortle 1 skies I will be under.
4. MELE Quieter 3C fanless, 12V, mini PC.
5. Pegasus Astro Pocket Power.  On loan from my other rigs.
6. SVBONY 30mm guide telescope.  Mounts nicely on the side of the AM5 leaving the ZS61 handle free for carrying.
7. ZWO ASI120 mini guide camera.
8. Large-ish Losmany-style mounting plate.
9. Not shown.  A mini low power smart wireless router, for setting up a local area network.  The network is set up and proven prior to my leaving, since I am a dunce when it comes to networking.
10. Things not used:  a) autofocuser.  Decided at this f.l. and pixel scale that I would probably not need to do much focussing.  And my couple nights bore that out.  In any case, if I am doing this remotely, I am likely to be out under the stars at Bortle 1 with the rig and available for the occasional twist!  b) Filter wheel.  Got the slider on and with only a OSC camera, not much to do there.  c) Counter weight and extension bar.  Not needed with this mount.  But I will bring a small weight to put in the tripod sling to lower the center of gravity and stability if wind happens.  d) Battery.  I'll have power at my cabin, so an extension cord will suffice.

On to the image:  This was probably not the best field of view for this small aperature lens.  This was taken over two rather short nights.  I lost a lot of data the first night because I am a bone head when it comes to setting up new computers.  If, when you set up a new folder on a new computer, without the proper folder attributes (such as allowing the folder to be written too!), and you fail to notice the error warnings from your sequencer that files cannot be saved, the sequence will nice chug along, but you will accumulate no images!  The image I present here at the time of this writing suffers from pre-processing errors that I have seen in other images.  Such as some stars looking like tiny donuts.  I have found with another image, that this artifact comes from the cosmetic correction function.  And I think CC does this in cohoots with drizzle, when used.  The solution is to ditch the CC function, which mostly I have detected very little issue with doing do.  But considering my much undersampled data, I was not about to ditch the drizzle.  So I am re-pre-processing this data as I write this and will replace this crummy image later if I get better results.  (UPDATED:  Revision C, the currently displayed full image did go through the repeated pre-processing, successfully eliminating the donut stars in the original.  It also improved other aspects.  This was a very quick processing to get it up and visible, to new viewers of this page.)  I also need to tweak the backfocus a bit to round the stars in the corners and also hopefully lose some color aberration in the stars.  But I am generally pleased with this as a first image.  Star Tools tells me that with this camera (large pixels), I should expect a "soft" appearance.  And that is true!   They also said that auto guiding should be more forgiving, and that certainly bears out.  The guiding was incredible and the small profile of the setup makes this rig very resistant to wind.  I need to set up targets in New Mexico where these limitations will be less of an issue.  Also, find them in southerly locations that I cannot see from my home.  I'll take suggestions!  One thing I can state for sure is a small aperature scope is the real cure for individuals who have become pixel peepers!  My first imaging telescope really was the RASA 11.  I have become very spoiled with that scope.  Fast, with very well resolved detail.  

As far as the AM5 performance.  I have only had it out a couple of times under working conditions.  I am very happy with it.  It is overkill for this sized scope.  I could have waited for the AM3 to come out, but that would have reduced my future-proof capabilities.  As it is, this rig, fully fleshed out as seen in the photo is trivial to lift and carry through the house, across the deck and 100 ft to the patio.  No counterweight and extension bar is a real plus.  In any case, I see this mount as an ideal match for a RASA 8, still with no need for counterweight.  If so, I will likely trade my 11 for an 8 in the future.  And the whole thing remains portable.  A number of users have complained that the AM5 has no multistar modeling available for accurate pointing models.  (I believe ASIair users do have that option.)  I personally remain resistant to adopting anything that continues to force me to purchase my gear from one source.  The issue is likely more important for visual observers using this mount.  I will explain below why this is a less important issue for astrophotographers.  My experience was that I could get good polar alignment with the setup.  But even this was not enough to allow me to acccurately point to a target, such as Vega accurately.  Even get Vega in my wide field.  Someone can correct me if I am wrong, but I feel that most polar alignment algorithms fail to take into account that the mount level may not be perfectly level.  So you get a perfect aim at the pole, but as you move away from the pole, there remains a deviation that increases with distance from the pole.  In any case, this reality can be a real pain for visual users.  For astrophotographers, plate solving very quickly resolves any slight misaiming issues such as that.  In my experience with this image I found that NINA was able to get me to near perfect center of my desired field after a single "go to frame - plate solve - recenter - confirmation plate solve"  cycle.  And the multi position polar alignment of NINA is a great partner with this mount.  The mount is very fast to slew, settle and even just a couple second exposure is sufficient to gather the necessary stars to do its thing, even in the not so dark dusk useless time of the session.  Becuase the mount appears to have no internal computer and memory I believe that ZWO would have a hard time implementing a star pointing model system for super accurate targeting.  I believe that my Celestron mount (and maybe many others) have their computers in their hand controllers.  The AM5 hand controller is super simple and I think dumb (meaning not sophisticated that way).  Its only to move the mount and do a few simple tasks and carry the WiFi capability.  I would suggest for that purpose, that if one is working visually within a certain location in the sky, that they find pointer objects, such as Vega, center, then sync with the planetarium program of their choice.  In that case, it is easier to then find object nearby.  But there is no means of the planetarium software to coordinate with the mount, as CPWI does with the Celestron mounts, for example.  Precision encoders would likely make all this mute.  But also very expensive for the visual observer, who would be driving a relatively small scope with this mount.

Comments

Revisions

  • Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle
    Original
  • Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle
    B
  • Final
    Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle
    C

B

Title: Travel Imaging Rig

Description: More details in the Description

Uploaded: ...

C

Title: As per Discussion, new pre-processing solved the donut stars and made other stuff better.

Description: See Description.

Uploaded: ...

Sky plot

Sky plot

Histogram

Sh2-101 (Tulip Nebula) to NGC 6883.   A First Light Project on a Travel Rig, Alan Brunelle