Thursday, May 25, 2017

Sun Compass - How to do a daytime polar alignment

One of the challenges of setting-up telescope equipment at a public star party is you need visible stars in order to polar align your telescope mount. But, it's just at that time that the visitors are curious and want to ask questions, God bless 'em.

So, for some time now, I've used the azimuth of the Sun (from the SkySafari Info screen below) to set-up my tripod before dark, or at any time of day, say for a solar observing event, such as an eclipse.

When the sun angle is 270° (Sun directly West), it's a piece of cake - arrange the two southward facing legs so that the shadows overlap. (See Morning Example, below.)

But, what do you do between Fall and Spring, when the Sun doesn't reach as far North as 270°? And, what if you want to set-up any other time of day? Maybe you waited too late and missed the 270° mark?

So, using the azimuth of the Sun reading, found in SkySafari, I used this contraption to line up it's shadow with the SS reading of 276° and 4 min.

Now, for this to work, one has to reverse the cardinal direction readings, since you want to point to where the Sun's shadow is coming from. Hence, 270° is on the right (east, as I'm looking at it). North is up.



















Also note this is not affected by the Equation of Time since that is figured in with the SS azimuth reading.

So, all one has to do is set this sun compass under or near your tripod, orient the shadow to agree with SkySafari's listed azimuth of the Sun (or, whatever source you customarily use) and aim your third tripod leg to where North is indicated.

Now, we just need a Star Party.

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Morning Example - taken when the Sun was at 75°.


M8 - The Lagoon Nebula 23-May-2017

Distance 4,100ly, in Sagittarius (per https://en.wikipedia.org/wiki/Lagoon_Nebula)

Telescope configuration: Explore Scientific ED102 FCD-100 Air-Spaced Triplet with the Explore Scientific 3" 0.7x focal reducer (fl=500mm, f/4.7).
Camera: Nikon D5300a (IR-modified). Exposure data: 10 - 30 second exposures at IS100.

Image capture scale: 1.63 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 158.9 arc-min. Image capture on-board camera controls with IR-remote.

Mount: Celestron AVX German equatorial mount (HyperTuned by Deep Space Products), unguided.

Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, Sigma Median Reject combined,
DDP, noise reduction in ImagesPlus Image Processing 6.5.
Adaptive Richardson-Lucey deconvolution (5x5 by 5 passes) in IP.

Cropped to final dimensions and resized to 50pct. Final image scale/resolution 3.26 as/p.

20170523_M8_CombSigMed-IPddp-IPadj2-NEBcrv-TPadj2-IPclr.jpg

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Monday, May 22, 2017

M27 - The Dumbell Nebula 21-May-2017


Distance 1,360ly, in Vulpecula  (per https://en.wikipedia.org/wiki/Dumbbell_Nebula )

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 4 - 10 minute exposures at IS800. Ambient temp ~69°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 24.9 arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, Min/Max Excluded Average combined,
DDP, noise reduction in ImagesPlus Image Processing 6.5.
Adaptive Richardson-Lucey deconvolution (7x7 by 7 passes) in IP.

Cropped to final dimensions and resized to 50pct. Final image scale/resolution 0.82 as/p.

Seeing: FWHM: 2.68 pixels, 2.19 arcseconds (per TSXPro ImageLink).

20170521_M27_CombExcAvg-IPddparl-TPcrp-IPadj-TPadj.jpg

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Friday, May 12, 2017

Autoguiding - Exposure Time vs Minimum Motion

Exposure_Time-vs-Min.Motion

Originally published 12-May-2010

Regarding, "Typically you will want to autoguide with exposures of 4-5 seconds to overcome effects of seeing ...", (from a Yahoo Group post), I believe there is a different school of thought developing on that point. From my experience, the key to avoid chasing the seeing is to increase your minimum motion rather than increasing exposure time. This enables using a so-called "mid-range" mount and making quick, responsive corrections. To my way of thinking, you want to choose an exposure time that provides a solid SNR but does not saturate. Then, separately, adjust your minimum motion/movement to accomodate seeing conditions. Using PHD Guide as one example, I typically examine the star profile and shoot for a nice sharp spike rather than a plateau. But, the error most commonly made is to leave the minimum motion set too low and then increase the exposure time, which bloats the guide-star. For example, I myself use an Orion ST80, 400mm f/5, with a Q-Guider, which has 5.2um pixels. The resulting image scale is of course 2.68 arc-seconds/pixel. But at the default minimum motion setting of .15 (pixels), that turns out to be .40 arc-seconds. That means PHD would issue a correction if it detected a move of .40 arc-seconds. That would be fantastic seeing, no? Even if you double that to allow for movement in either direction, that's still .80arc-seconds. For most of us, seeing is around maybe 2 arc-seconds. In practice, I typically set exposure to 1.5 seconds. But, if the star I want is bright enough, I'll go down to 1 second, again, to get a nice sharp guide star, and let the min. motion take care of chasing the seeing. I've used anywhere from .25 pixels to .40 pixels min. motion. I've also seen it advocated to reduce aggressiveness. That is the last factor to adjust - again, it has nothing to do with seeing. Once you have the above factors determined, if you're consistently overshooting, i.e., bouncing back and forth (overcorrecting), reduce it. If your corrections generally take 2 or 3 moves in the same diection to get the star back where it belongs, increase it. So, in summary, use exposure time to provide good data for the centroid calculation and deal with chasing with the parameter designed for that purpose - the Minimum Motion Setting.

Thanks and regards,
Bill Shaheen Gold Canyon, AZ\ USA

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Wednesday, May 10, 2017

M57 - The Ring Nebula 29-Apr-2017



















Distance 2.3kly (per https://en.wikipedia.org/wiki/Ring_Nebula )

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: Best 10 of 12 images at a variety of exposures between 180 and 360 seconds at IS800. Ambient temp ~49°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 15.5 arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with a QHY5L-II monochrome planetary & autoguider camera, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, HDR Adaptive Add Average combined.
Stretching and DDP in ImagesPlus Image Processing 6.5.
One pass unsharp mask in ThumbsPlus v10.

Cropped to final dimensions and resized to 50pct. Final image scale/resolution 0.82 as/p.

Seeing: FWHM: 3.04 pixels, 2.49 arcseconds (per TSXPro ImageLink).

20170429_M57_CombAdpHDRAddExc-IPstr-TPadj3.jpg

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M13 - The Hercules Globular Cluster 29-Apr-2017

Distance 22.2kly (per https://en.wikipedia.org/wiki/Messier_13 )

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: Best 9 of 11 images at a variety of exposures between 30 and 180 seconds at IS800. Ambient temp ~53°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 41.1 arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with a QHY5L-II monochrome planetary & autoguider camera, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, Sigma Clipped Average combined.
Stretching and DDP in ImagesPlus Image Processing 6.5.
One pass unsharp mask in ThumbsPlus v10.

No cropping; resized to 50pct. Final image scale/resolution 0.82 as/p.

Seeing: FWHM: 2.80 pixels, 2.30 arcseconds (per TSXPro ImageLink).

20170429_M13_CombSigAvg-IPddp-TPadj.jpg

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M16 - The Eagle Nebula in Serpens 22-Apr-2017

Distance 7,000 ly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 6 - 10 min. exposures at IS800. Ambient temp ~58°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 22.2 arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with a QHY5L-II monochrome planetary & autoguider camera, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, Sigma Clipped Median combined.

Cropped to final dimensions and no resizing. Final image scale/resolution 0.41 as/p.

Seeing: FWHM: 3.69 pixels, 3.02 arcseconds (per TSXPro ImageLink).

20170422_M16_CombSigMed-IPddpadj-TPcrop-TPadj-IPnr-Crop2.jpg

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M104 - The Sombrero Galaxy in Virgo 25-Mar-2017

Distance 31.13 ± 0.42Mly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 10 - 10 min. exposures at IS1600. Ambient temp ~53°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 35.5arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 9 bias frame master and 0 flat frames, Sigma Clipped Median combined and finished with a one pass unsharp filter in ThumbsPlus 10.

Cropped to final dimensions. No downsizing. Final image scale/resolution 0.41 as/p.

Seeing: FWHM: 2.92 pixels, 2.39 arcseconds (per TSXPro ImageLink).

20170324_M104_CombSigMed-IPddpadj3-TPadj-INP.jpg

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NGC3169/3166/3165 (l-r) - Galaxy grouping in Sextans 23-Mar-2017

Distance 57Mly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 7 - 8 min. exposures at IS1600. Ambient temp ~50°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 25.2arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 0 bias frame master and 0 flat frames, Min/Max Exluded Average combined.

Cropped to final dimensions. No downsizing. Final image scale/resolution 0.41 as/p.

Seeing: FWHM: 3.26 pixels, 2.67 arcseconds (per TSXPro ImageLink).

20170323_NGC3169_CombExcAvg-IPddp-Crop-TPadj-INp.jpg

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Horsehead 31-Jan-2017 Using Summed Luminance

This image was taken as part of testing TSXPro's Summed Luminance capture option. Dustmotes removed using Inpaint.

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 2 - 10 min and 5 - 15 min. exposures at IS1600. Captured with TSXPro Camera Add On from Software Bisque using Summed Luminance mode.

20170131_HorseHead-mono_CombSigMed-IPddp-TPadj.jpg

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M82 - The Exploding Cigar Galaxy in Ursa Major 20-Feb-2017

Distance 11.4-12.4 Mly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 6 - 8 min. exposures at ISO1600. Ambient temp ~42°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 27.9arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 0 bias frame master and 0 flat frames, Min/Max Sigma Clipped Median combined.
Cropped to final dimensions. No downsizing. Final image scale/resolution 0.41 as/p.

Seeing: FWHM: 4.01 pixels, 3.29 arcseconds (per TSXPro ImageLink).

20170223_M82_CombSigMed-IPddp-TPadj1-IPadj.jpg

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NGC2903 - Spiral Galaxy in Leo 20-Feb-2017

Distance 30.6 ± 4.6 Mly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 9 - 8 min. exposures at ISO800. Ambient temp ~53°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 22.5arc-min. Image capture using TSXPro Camera Add On (Software Bisque) via BackyardNikon.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 0 bias frame master and 0 flat frames, Min/Max Sigma Clipped Median combined.
Cropped to final dimensions and resized to 50pct. Final image scale/resolution 0.82 as/p.

Seeing: FWHM: 3.06 pixels, 2.50 arcseconds (per TSXPro ImageLink).

20170220_NGC2903_CombSigMed-IPddpadj-TPadj.jpg

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M1 - The Crab Nebula 25-Jan-2017

Distance 6500 +/- 1600 ly. North is up, east to the left.

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300a (IR-modified). Exposure data: 2 - 8 min. exposures and 5 - 10 min. exposures at ISO800. Ambient temp ~40°f.
Image capture scale: 0.41 arc-seconds/pixel (i.e., un-binned). Field of view (horizontal) = 13.6arc-min. Image capture using TSXPro Camera Add On (Software Bisque).
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) (without the Starlight Xpress SXV-AOLF (Adaptive Optics Large Format) device) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 0 bias frame master and 0 flat frames, Min/Max Sigma Clipped Median combined.
Cropped to final dimensions of 2000x2000. No downsizing. Final image scale/resolution 0.41 as/p.

Seeing: FWHM 6.28 pixels, 2.57 arcseconds

20170125_M001_CombSigMed-IPddpadj-TPadj.jpg

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NGC891 - Spiral Galaxy in Andromeda 26-Dec-2016

Distance 27.3 ± 1.8 Mly

First light after removing the MoonLite Focuser and restoring the 2inch PreciseParts Adapter.

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300 (unmodified). Exposure data: 6 - 10 min. exposures at ISO800. Ambient temp ~50°f.
Image capture scale: 0.41 (reduced from 0.43 as/p due to replacing the focuser with the Precise Parts adapter) (un-binned). Field of view (horizontal) = 25.5arc-min. Image capture using TSXPro Camera Add On (Software Bisque).
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) (without the Starlight Xpress SXV-AOLF (Adaptive Optics Large Format) device) using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 0 bias frame master and 0 flat frames, Min/Max Exluded Average combined. Cropped to final dimensions of 3743x2940. No downsizing. Final image scale/resolution 0.41 as/p).

20161226_NGC891_CombExcAvg-IPddpadj.jpg

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Sunday, April 16, 2017

Featured/Recommended Products


From time to time, we in the Superstition Mountain Astronomical League are frequently asked for recommendations of astronomy related products and services. Our members have an extensive knowledge base and own most of the products featured below.



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