sponsored by psychohistorian.org

DOCdb

Deep Sky Observer's Companion – the online database

 

Welcome, guest!

If you've already registered, please log in,

or register an observer profile for added functionality.

List:

log in to manage your observing lists

 browse:

 

 position:

 

 next:

 

 options:

summary

rename

prune

trim

remove

close

copy

combine

plan

bookmark

load

new

delete

marathon

favourite!

Full database:

Entire DOCdb database of 18,816 objects.

 browse:

 position:

IC 1140 (13,274 of 18,816)

 next:

oc gc pln bn dn gx gxcl ast aka lost

Object:

list

bookmark

finder chart

altitude today

altitude (year)

 search:

½°, , in DOCdb

show browsing

IC 1140

IC 1140

RA: 15h 49m 25.3s
Dec: +19° 06′ 52″

Con: Serpens
Ch: MSA:691, U2:155, SA:7

Ref: Corwin (2004), Steinicke (2009)

(reference key)

Type: stars (three)

Mag: B=?, V=?

Size: ?
PA: ?

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

IC 1140. The IC1 position falls on an empty patch of sky. There are stars and asterisms in the area, but nothing leaps out as a "vF (? S Cl)" as Dreyer characterizes this in the IC. The "* 9.5 close" is indeed near the nominal position, but this does not help in identifying Bigourdan's object. Could this be another case like NGC 2529 and 2531 (which see), imaginary nebulae beyond the limit of detection?

Checking his big table, we find that Bigourdan saw the object twice. He estimated its position on both nights with respect to a nearby star, which he called "An. b", to be PA = 120 degrees, distance = 1.3 arcmin. He tells us that "An. b" is +8.5 seconds and +2.5 arcmin from BD +19d 3021. There is a star there, so I've reduced his estimated position using a position for the star that I measured on DSS. This leads directly to an asterism of three stars that match Bigourdan's description perfectly.

So what went wrong? Checking the list of new nebulae in CR 112, 703, 1891 in which this object appears, we find that his position (copied faithfully into IC1 by Dreyer) does not agree with the correctly reduced position. Further, his description reads, "... [the new object] is situated near BD +19d 3021 at p = 120 degrees, d = 1.3 arcmin."

He must have confused his observing records and used the position of the BD star for his reduction. (He did, in fact, use the BD star, but only to estimate the position of "An. b".) As I found, when we use his correct comparison star, his estimated position falls almost exactly in the asterism.

When Bigourdan prepared his vast set of observations for publication in 1912, he must have re-reduced the positions of all of his new nebulae. I1140 has its correct position in the tables of new nebulae. I suspect that the reason Bigourdan did not notice the mistake is that the position was precessed to equinox 1860 for the 1891 CR list, while the 1912 list is for equinox 1900.

Favourite lists

Lacaille's catalogue

The Messier objects

Dunlop's catalogue

The Bennett objects

The Caldwell list

Named DSOs

Object search

First search phrase

    and

Second search phrase

Type of object to include:

open cluster
globular cluster
planetary nebula
bright nebula
dark nebula
galaxy
galaxy cluster
asterism & stars
unverified/lost
nova

The Bug Report

DOCdb is still in beta-release.

Known issues, feature requests, and updates on bug fixes, are here:

> Bug Report

Feedback

Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!

> Contact us

Help!

DOCdb is a free online resource that exists to promote deep sky observing.

You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.

> Find out more

Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.