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G11 performance unguided
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I have been experimenting with optimizing unguided performance with my G11 and wanted to share an example of what's possible right now.? Most importantly, this is unguided and at a pretty good focal length. My G11 was purchased around 2010 and has been steadily updated through the years. I think it's pretty much what you'd get if you bought it today, except it's pretty banged up lol the target is webo 1, a tiny planetary nebula on the fringe of the heart nebula.? this is a single 300 second frame (Ha filter) scope is ES165?@844mm focal length, i think it's at f5.6? i have to check the reducer specs camera is SX trius pro 694, no cooling (camera issues with cooler) unguided exposure no PEC the important stuff on the exposure fwhm 1.914 eccentricity 0.5140 (roughly, star eccentricity?of 0.5 is considered round to the human eye) I hope i used settings that represented a good test (I used the Ha filter because otherwise my luminance or other broadband filter would blow out due to bortle 9 skies)? ? i've attached a JPG to this email, it's an unimpressive target but the star profiles show the performance (it's not cut off: i'm aiming for the edge of the nebula where webo 1 resides) the link to the raw fits is here if you want to pixel peep this was one of the best frames, and of course image quality varied quite a bit Observations: Polar alignment and tightening the alt/az knobs seem to be really critical, far more than I anticipated. I used sharpcap 3.2 for polar alignment (ended up measured at 14") and replaced the stock bolts with #8 hardened hex head bolts (nuts for the az), and tightened them carefully using a crescent wrench.? I also took care to balance the mount in both ra and dec (using spring loaded worms, so no weight bias) and another important thing was not to overtighten the clutches: only as much as needed to stop the axis moving I don't think this says I can image unguided all the time just yet. there are still a fair number of frames that show some star elongation, enough that i can see it at 200% magnification. I'm not sure if it's polar alignment or other, so i'm still experimenting -- Brian? Brian Valente portfolio |
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Sonny Edmonds
So if I understand this correctly, you took a 5 minute exposure, unguided (Meaning this is just the Gemini (II?) holding the aim mechanically?
It appears amazingly sharp for 5 minutes unguided. Quite a credit to the Gemini and the mechanics of the Losmandy mount. Very nice test Brian, and encouraging results. Your dropbox file is a .fit format though. What do you use to work with .fit files? |
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Yes sonny, and just to be clear it's at 844mm focal length, not widefield regarding fits files, that's the standard for astronomical cameras, and there are many options to work with them. personally i use PixInsight, but I also use CCDStack (for checking things), SGP reads and writes them, and occasionally i use astro pixel processor On Sun, Feb 2, 2020 at 7:42 AM Sonny Edmonds <sonnyedmonds@...> wrote: So if I understand this correctly, you took a 5 minute exposure, unguided (Meaning this is just the Gemini (II?) holding the aim mechanically? --
Brian? Brian Valente portfolio |
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Regarding FITS files:
From 1995 to about 2002 I worked as a programmer on the Sloan Digital Sky Survey (I was one of a team of 4 programmers that wrote the data acquisition code - in the VxWorks operating running on multiple Motorola single board computers all tied by a vertical bus interconnect to an SGI IRIX computer - that read out the 54 CCD¡¯s from the imaging camera, the 4 CCD¡¯s from the spectrographs, the CCD on the photo metric camera, in realtime, writing the data redundantly to DLT tape drives and doing realtime, online, flat-fielding and star detection). One of my first programming assignments upon joining the project was to write a FITS file verifier, intended to ensure that all of the FITS files written by the data acquisition system and by the data processing pipeline were legal FITS. ?So I became a sort of FITS lawyer. ?Like all professional astronomy projects, raw and in many cases processed data were all stored in the FITS format. ?Even at that time FITS was an old format; in fact, the standard FITS record is limited to 80 characters because the files used to be written to punched cards (¡°Hollerith cards¡±). ? Perhaps the best thing about using FITS for your personal astrophotography files is that in addition to recording the image data, FITS optionally records a lot of metadata. ?So my files, mostly written by SharpCap, have info about the camera, gain, offset, position on the sky, filter wheel position, date and time, target name, etc.. ?That metadata is invaluable for later processing (and PixInsight, for example, will add additional FITS records describing noise and other statistics, alignment matrices, and so forth). |
¿ªÔÆÌåÓýCoincidentally, just last night I discovered the 80 character FITS record format, kind of accidentally. First thing I did was write a little script to spit out the header with newline-terminated records to facilitate using text processing tools on the header info.?Don, do you have handy a pointer to the FITS spec so I can see what stuff I can add to the files without getting in trouble with you lawyers? ??-Les On Feb 2, 2020, at 10:30 AM, Don Holmgren <djholm@...> wrote:
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Sorry, a bit more spam, but SDSS was a project all of us were very proud of.
Here's a paper for an IEEE Realtime Conference talk I wrote about the data acquisition system which also details the various instruments: SDSS operated one of the very first web servers in the United States.? Well before Google existed (but Alta Vista was already around), we implemented in 1995 a search engine using WAIS that allowed the astronomers to do context sensitive searches through all of the documentation.? For more about SDSS, see and in particular .? |
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one more update on this
i've still been working on unguided imaging @844mm focal length (about 1 arcsec/pix resolution) this is 80x300sec Ha filter of M81, totally unguided on my G11 processing is just calibration and registration of images, no cropping, a bit of stretching and a little HDRMT for the core (wanted to confirm i could see the dust lanes) visually an unremarkable image, but technically i think it reinforces how good the stock G11 can perform |
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-------- Original message --------
From: Brian Valente <bvalente@...>
Date: 2/4/20 11:15 AM (GMT-06:00)
Subject: Re: [Losmandy_users_io] G11 performance unguided
one more update on this
i've still been working on unguided imaging @844mm focal length (about 1 arcsec/pix resolution) this is 80x300sec Ha filter of M81, totally unguided on my G11 processing is just calibration and registration of images, no cropping, a bit of stretching and a little HDRMT for the core (wanted to confirm i could see the dust lanes) visually an unremarkable image, but technically i think it reinforces how good the stock G11 can perform |
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Yes. I hadn¡¯t done the math but you¡¯re right. Over 3 nights On Tue, Feb 4, 2020 at 1:51 PM Sonny Edmonds <sonnyedmonds@...> wrote: Very nice Brian. --
Brian? Brian Valente portfolio |
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Quite impressive! Really shows the mounts precision!
I used to break down my G3 camera into chunks of time, like 300s, 600s, 900s, 1200s... up to 1800s (30 minutes) for one shot images. Nobody could get the fit files to stack. But I could stack with time, as one friend told me. I'm still interested in doing that. But my G3 is now a fishing weight. And my Atik Infinity stacks for itself. Longer than 120s gets hot pixels. I wish Losmandy would get back to me. I called and left a message, but bet they are suffering jet lag. I'd be suffering from dead butt after flying back from GB. -- SonnyE |
¿ªÔÆÌåÓýSonny, I dont know what the hold up at Losmandy is, I ordered my G11 from Highpoint Scientific and it was drop shipped with all the upgrades from Losmandy in two weeks and Highpoint paid the shipping, I think Losmandy charges about $150.00 to
ship.
Sent from my Galaxy Tab A
-------- Original message --------
From: Sonny Edmonds <sonnyedmonds@...>
Date: 2/4/20 3:51 PM (GMT-06:00)
Subject: Re: [Losmandy_users_io] G11 performance unguided
Very nice Brian.
Just curious, but 80X300sec, is that 80 each, 300sec images. Or 6.66 hours? That's phenominominomal! -- SonnyE |
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Sonny give them a call tomorrow. I stopped by the shop for something unrelated and I know they are working out from under the backlog since returning from the UK show On Tue, Feb 4, 2020 at 4:48 PM Sonny Edmonds <sonnyedmonds@...> wrote: Quite impressive! --
Brian? Brian Valente portfolio |
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I would not say they have a showroom. they don't really have products out you can test or see fully assembled, though there are mounts all over the place.? I don't work for them, so i can't really say what is their policy, but i'm pretty confident if you told them what you wanted and arranged ahead of time, they would be happy to host you and handle your order On Wed, Feb 5, 2020 at 9:03 AM Sonny Edmonds <sonnyedmonds@...> wrote:
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Brian? Brian Valente portfolio |
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I wanted to reiterate, the key is coordinating ahead of time. They are usually backordered on a lot of stuff, so I would not go in expecting to just add any accessory, it just may not be available for you to walk out with.? On Wed, Feb 5, 2020 at 9:03 AM Sonny Edmonds <sonnyedmonds@...> wrote:
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Brian? Brian Valente portfolio |
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PPS - parking is pretty bad lol. but for one car you can find some space On Wed, Feb 5, 2020 at 9:03 AM Sonny Edmonds <sonnyedmonds@...> wrote: Thanks Brian! --
Brian? Brian Valente portfolio |
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Sonny Edmonds
Oh, I can understand not having a "store front". They machine and sell. Nothing would get done if they stopped for every Tom, Dick, and Harry, and a mirad of senseless questions. Most are answered right in the videos.
I'll do my fondling in private. LOL! Not on the showroom floor. I abhor someone picking something up and messing with it. But somebody at the door willing to pay $4,000 for a product should be appealing to them. Bring out the boxes, pay, load, and go. No shipping. One of my questions that I must see to answer is: GM811GHD, or G11G? I'm going to put a fly on the mount, figuratively speaking. I'm waiting for a call back after Scott gets in. She thinks they can accommodate me on an ASAP basis. -- SonnyE |
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One of my questions that I must see to answer is: GM811GHD, or G11G? why would you consider the GM8 over the G11? On Wed, Feb 5, 2020 at 10:25 AM Sonny Edmonds <sonnyedmonds@...> wrote: Oh, I can understand not having a "store front". They machine and sell. Nothing would get done if they stopped for every Tom, Dick, and Harry, and a mirad of senseless questions. Most are answered right in the videos. --
Brian? Brian Valente portfolio |
On 5 Feb 2020, at 10:27, Brian Valente <bvalente@...> wrote:Not to answer for Sonny, but from my perspective the G11G is only $300 & 6# more than the GM811GHD, not much for a significant increase in capacity. And, the G11 comes with twice as much counterweight, a $75 bonus!why would you consider the GM8 over the G11?One of my questions that I must see to answer is: GM811GHD, or G11G? Perhaps the only reason I¡¯d go for the GM811, if I were shopping, would be to avoid the temptation to go all the way to the G11T. ;) -Les |
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