Harold Corwin

If this is the big galaxy that I think it is -- ESO 139-G012 -- it suffers from errors in not just its IC RA (1860 only), but in its original RA and Dec as well. I do not believe that this can be the much fainter ESO 139-G010, even though that is within 3-4 arcmin of Frost's nominal position. Though Andris lists the IC number for this galaxy in ESO-B, he put a query on the IC number.

Frost found this on a Bruce plate taken at Arequipa. He found only two other nebulae on this plate, IC 4646 and IC 4652, both close to their nominal positions. Both are fairly good-sized galaxies, and IC 4652 has a description that is identical to IC 4658's: "F, plan. magn. 15." Thus, we should look for an object that is similar in appearance to IC 4652.

That object is ESO 139-G012. It is 1.5 minutes following and 20 arcmin south of Frost's nominal position, close enough to "digit errors" to suggest some sort of transcription or procedural error. I've therefore adopted the object as IC 4658, though with a cautionary colon to flag the identification as uncertain.

As a reality check, I calculated the distance of the galaxy from the center of Frost's plate (17 24 17, -57 32.7 for 1950) -- is the galaxy really on the plate? The answer is yes, it is 158 arcmin from the center while the edges of the plate (6.3 x 6.3 degrees) are 189 arcmin from the center. This is comparable to 149 arcmin for IC 4646 and 130 arcmin for IC 4652, though perhaps it is farther enough than those two to have led to the position problem.

Well. We obviously need to check this on the plate, hopefully still at Harvard.

The IC RA? Dreyer made a 1 minute error when he precessed it to 1860; the 1900 IC RA is correct.

― IC Notes by Harold Corwin

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

A complete list of credits and sources can be found on the about page