Comet Neowise and Venus


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Welcome to taosastronomer.com!

offering local "hands-on" observing
(visual and imaging) sessions and instruction
viewing and imaging from Rabbit Valley Observatory
a dark sky location on the mesa just west of Taos, NM

 

Rosette Nebulae

Image obtained March 02-03, 2022 through RVO's Explore Scientific’s 127mm ES127ED APO refractor resulting in an 952mm f/7.5 optical system and incorporating a HOTECH field flattener -- and employing RVO's new ZWOASI2400MC Pro Sony CMOS-chipped premium one shot color astronomical camera -- 19 of 20 carefully selected and stacked 240-second color light frames combined with multiple dark, flat and bias calibration frames shot at a Gain setting of 240 / Offset = 50 and using Astro Photography Tool image-acquisition software -- totaling 76 minutes effective luminance; this data used to create the above image. The optics were driven by the Hypertuned Losmandy G-11 mount equipped with Ovision's precision RA worm gear, guided with a ZWO ASI 120MM Monochrome CCD camera through a 60mm guidescope using PhD2 guiding software and post-processed with ASIStudio, DeepSkyStacker, CCDStack2, and Photoshop CS6 s/w.

Photographer's note: It is instructive to compare the image above, taken with the superior Explore Scientific apochromatic 127mm refractor (3 optical elements, virtually no false color fringing) and shot with the new ZWOASI full-framed camera with my older previous effort of this well-known object, linked here. The previous image of this very object although beautiful and quite colorful, was captured with a high quality but nevertheless a 2 optical element Williams' Optics Megrez achromatic refractor, and with a uncooled Canon 450XSi, modified for deep-sky use. The difference in the detail (especially noting the stars' lack of significant fringing coloration (halos around stars) and general resolution is extraordinary, due in part to the larger objective lens -- 127mm vs. 80mm -- but also due to the optical type (apochromatic vs. achromatic). Click this link for a discussion of telescopic lens optics. Also, in the case of the original shot, the computer post-processing steps necessary to end up with a acceptable shot was very extensive. The Rosette image as above required no such rigor in post-processing -- the photographs straight out of the camera were really quite good (although dim, process linked here), requiring really only calibration and stacking; followed by only some minor Photoshop adjustments and mild sharpening. Frankly, after calibration, there was virtually no sharpening or noise reduction needed in post-processing. The new image also displays much less "noise" -- that is because the camera is cooled to far below ambient, rendering it more sensitive and noise-free. Click on this text for a link to the steps involved with the acquisition and post-processing of this image. For another astrophotographer's ongoing adventure with this object, please click this linked text.

Below is a new astrophotography compilation log feature, recently developed here on this website, and inspired by the book The Astrophotography Manual, by Chris Woodhouse -- highly recommended and linked here.

Subject Name -- Rosette Nebulae and Clusters Catalog Name -- NGC 2237-39 and NGC 2244 RA 06h 31' 56" DEC +04°56' 35' Time Rise -- 02:42PM Transit -- 08:59PM Time Set -- 03:16AM
Observing Location -- Rabbit Valley Observatory, El Prado NM 87529

Longitude -- 105° 37' 38.59" W

Latitude -- 36° 25' 11.54" N Altitude -- 2095 meters Date -- 03-02-2022 Beginning set-up time -- ~6:45PM MST Imaging Start Time -- 7:44PM MST
Weather Temperature F -- ~36°F at start Wind -- negligible        
Conditions -- Very clear Seeing -- Excellent -- Bortle 3-4 Transparency -- Excellent Cloud Cover -- none Moon Phase -- 29.5 days (new)    
Telescope Optics -- ES127ED Aperture -- 127mm FL -- 952mm Reducer -- none Imaging FL -- 952mm Focal Ratio -- f/7.5  
Imaging Camera -- ZWOASI2400MC Pro (full-frame OSC)
Sony back-illuminated IMX410 full frame format14-bit ADC CMOS sensor -- 24MP
Pitch in microns -- 5.94 square W (px) -- 6072 H (px) -- 4042   Well Capacity -- 100ke
Read noise -- 1.1e to 6.4e
Guider Camera and software -- ZWOASI120MM / PhD2 Guidescope -- 240mm f/4 Pitch -- 3.75 microns square W (px) -- 1280px H (px) -- 960px Guide Rate -- .5 sidereal RMS error total -- 1.21 arc-seconds / guide exposures of 3 seconds
Imaging Camera Details and Calculation Exposure time -- 240 seconds
Gain set -- 240
Offset -- 50
Number of Light Exposures -- 20
Binning 1X1 Camera cooled to ~10°F during exposure Filter -- none Imaging Resolution -- 1.287 arc-sec per px -- per astronomy.tools Polar alignment error via PhD2 -- 10.2'
Imaging Software Acquisition -- APT Calibration -- APT & DSS 19L, 22D, 20F, 20B frames used Initial conversion -- ASIStudio & CCDStack2 Post-Processing -- PSCS6 Sharpening -- NeatImage
General Comments and details -- See log #2 , 2022


Used Bahtinov mask, was perfect "close" per get-go, will try auto-focus next time / electric focuser is Rigel's nSTEP

 

  Cooled to a lower temp this time (10 degrees F), camera had no trouble attaining this temperature   Guiding error less than imaging resolution -- should suggest tight images Need to develop a folder of dark and hot pixel frames for the guider, as well as hone in on the focus

 

 

[copyright Rabbit Valley Observatory/Willis Greiner, 2022 -- all rights reserved]

 


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(all content copyright 2015-2022 Willis Greiner Photography, all rights reserved)