What are the .apd files that are included with CSOG?
They are AstroPlanner planfiles.
Wat are the .txt, .lst, .hct and .mtf files that are included with CSOG?
They are, respectively: Argo Navis User Catalogs, EQTours, NexTours and Autostar Tours.
Why are CSOG's observing guides pdf's?
PDF is the only truly cross-platform format. An image or e-book just won't do.
Why is CSOG not available in print?
Please read the size of CSOG on the CSOG 3.0 Release Notes page.
How many CSOG editions are there?
80 + 2 Observing aids: 3 Constellation editions by telescope aperture, 6 Catalogs & Lists, 15 Galaxy editions, 22 Nebula editions, 23 Star Cluster editions, 6 Observing Programs, 1 Binocular edition, 1 Double Star edition and 3 Other editions.
In addition to the regular CSOG content there a periodical observing guides for Deep Sky Forum's Object of the Week, the Webb Deep-Sky Society's Objects of the Month & Object of the Season, Astrotreff's Object(s) of the Month and Cloudy Night's Monthly Challenge Objects.
How many deepsky objects are in CSOG?
CSOG 3.0, published in November 2024, CSOG contains approximately 16000 (sixteen thousand) individual deepsky objects. Quite a few galaxy pairs and groups, or open clusters with an involved nebula, are combined into single CSOG objects. Including combined objects, I estimate the total number of deepsky objects in CSOG to approach 18000.
What is the most "complete" CSOG edition?
There is no single edition that contains every object that is included in the CSOG collection. But if I had to pick one, I would pick the 12-14" Constellation edition; only extremely faint objects such as some of the Arp galaxies, Hickson groups, very faint nebulae, etc. are not included in this edition.
Where do I go to see samples of CSOG?
Hundreds of samples of CSOG observing guides are given in observing blogs and in content such as Deep Sky Forum's Objects of the Week, the Webb Deep-Sky Society's Objects of the Month & Season, Astrotreff's Objects of the Month and Cloudy Nights' Monthly Challenge Objects.
Is there an image for every single object in CSOG?
With the exception of double star editions, all but one object have a DSS image centered on the object: A depiction of the constellation Ursa Major taken from AstroPlanner is used for the open cluster Collinder 285.
"By object" guides for galaxies and a few planetary nebulae also contain an SDSS image, when within the SDSS footprint.
What are the angular dimensions of the images used in CSOG?
As noted on the Observing Guides page, images are 30'×30' (half a degree) in size, unless noted otherwise.
Why are CSOG guides such large files?
Almost every image in CSOG is uncompressed; in full resolution. This allows zooming in on objects on a computer or tablet, without the image immediately becoming blurred and grainy. The uncompressed images are a unique feature of CSOG.
Also, in this day & age no one ought to be afraid of a gigabyte.
Why are some images in the guides much darker than others?
A few years back, the contrast of DSS images was greatly increased, making the images appear much darker. The advantage is that these images appear much nicer to the eye. The disadvantage is that subtle details, such as the fainter outer regions of galaxies, are much more difficult to perceive and are often not visible anymore at all.
Where I find it useful, I am replacing older, lighter images with the darker ones. That, however, is a lot of work given the size of CSOG. Time I would rather spend creating new CSOG editions. Replacing light images with darker ones is therefor a work in progress.
Will there be updates?
Yes. CSOG is a digital publication, allowing for relatively easy updates. With CSOG 3.0 being the last release in which every edition was updated simultaneously, new editions will be added incrementally and existing content will receive interim updates.
V1 was published in October 2012. CSOG 2.0 was released in December 2013, an interim update followed in January 2014, alongside the release of the Herschel edition. CSOG 2.1 was released on 18 March 2015, along with the new Arp, Holmberg, Dolidze, Dolidze-Dzimselejsvili and Stock editions. The number of editions doubled with the release of CSOG 2.2 in September 2016. With the release of CSOG 2.3 the number of observing guides doubled compared to CSOG 2.2.
In July 2020 CSOG's first double star edition was published: Struve Double Stars. In January 2021 Deep Sky Forum's Objects of the Week were added as weekly downloads, in April 2021 the Webb Deep Sky Society's Objects of the Month and Objects of the Season were added.
CSOG 2.4 was published on 23 June 2021 and brought further improvements and new editions.
CSOG 3.0 was published on 29 November 2024: here are the release notes.
For more information, please read Future CSOG.
How do I keep posted of website / CSOG updates?
Please subscribe to receive Clear Skies newsletters by e-mail and join the Clear Skies group on Groups.io.
I found an error / mistake / inconsistency / cosmetic issue / broken download link in CSOG... should I report it?
Yes, please do! Before you do so, please do check the Interim Updates page to see if it was already recognized.
How long did it take to write CSOG?
I first started working on the CSOG concept in September 2001. In its current form in April 2008.
CSOG V1 took 4½ years to complete: Compiling and sorting object lists, creating observing guides, collecting (and correcting) data and coordinates, adding images, creating AstroPlanner planfiles, compiling tours, creating mirrored editions, exporting content for publication, etc. Compiling guides for the constellations of Dorado and Mensa that include the Large Magellanic Cloud, took a complete year.
Updating CSOG 2.2 to 2.3 took 3 1/2 years, with V2.4 following a year later. CSOG 3.0 took another 3 1/2 years.
Is CSOG for GOTO telescopes only?
To the contrary. All CSOG objects include epoch J2000.0 coordinates. The coordinates can be plotted on the starchart you already own. If your starchart does not include the object, simply plot the position and make your starhop. Once close to the object's position, the DSS image in the guide takes over, leaving no doubt whether or not you found the targeted object.
Tours and AstroPlanner planfiles, but no SkySafari observing lists..? Celestron's SkyPortal app..?
SkySafari is an application that allows creation of custom observing lists. However, objects have to be present in the SkySafari object database. If an object is not in the database, it can not be added. As CSOG contains many thousands of objects that are not included in the SkySafari database, CSOG SkySafari observing lists can not be created at this time.
Hopefully a true "user objects" feature will be added to SkySafari in a future update. A simple "R.A. / Dec. / Object name" format will do.
The same goes for any other application that lacks a user object option. Really all that is needed is a simple "Name - R.A. - Dec." format (in epoch J2000.0). After all, all that is required is a designation and "X marks the spot" by means of a coordinate.
DSS Images, but no sketches?
CSOG contains well over 16000 objects. Sketches for all of these objects simply do not exist.
But what about sketches for a limited number of objects, such as the Messier edition or the Herschel 400? The problem is that sketches do not provide for a standard candle. By definition they are a subjective representation of any object, dependent on the sketcher's equipment, orientation, eyesight, artistic abilities, atmospheric conditions at the time of observation and of course the objects' elevation.
For sketches to be truly useful and an objective representation of what any object looks like through the eyepiece, all drawings must be comparable. A star of any magnitude must be drawn equal in size every time so as not to confuse them with brighter or fainter ones. Orientation and image size must be identical and, preferably, the object must be at similar elevation to limit atmospheric effects.
Such sketches simply do not exist. No matter how beautiful a sketch may look, the usefulness for visual astronomy is very limited, especially when considering the huge number of objects in reach of moderately large amateur telescopes.