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NGC 5298 (11,809 of 18,816)

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NGC 5298

NGC 5298, AGC 30103, ESO 445-39, LEDA 48985, MCG-05-33-015, SGC 134545-3010.8, h 3538, GC 3653

RA: 13h 48m 36.5s
Dec: −30° 25′ 42.8″

Con: Centaurus
Ch: MSA:889, U2:371, SA:21

Ref: SIMBAD

(reference key)

Type: galaxy, Sb

Mag: B=14.06, V=13.09

Size: 1.479′ x 0.66′
PA: 69°

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

NGC 5298. Steve Gottlieb has suggested that the traditional identification of N5298 with ESO 445- G039 may be wrong. Is it possible, he asks, that ESO 445- G035 is the galaxy that JH saw? His reasoning is that, relative to JH's observation of N5302, N5298's position is closer to G035 than it is to G039. This is probably also the source of the RC1, GHD2, and RNGC identifications: they, too, choose G035.

It looks to me like the most likely explanation is a simple +30 second error in JH's RA for N5302, and that his position for N5298 is good. Here is my thinking.

JH found 34 nebulae during Sweep 564 on 30 March 1835. Comparing his data for that night with those for the same objects from other nights, he seems to have had about his usual problem rate (5-10 percent) -- missed nebulae that he could have picked up, nebulae refered to nearby objects rather than being measured themselves, etc.

Seven of the objects from sweep 564 are in what became ESO/SRC field 445, so I looked at the offsets from the ESO positions in that field. I found, as Steve did, that NGC 5302 is off the modern position by +31.3 seconds of time, and that JH's position for N5298 is +26.0 seconds off if he saw G035 rather than G039. Looking at the offsets for the other nearby objects, though, I don't see any other large offsets:

NGC Delta RA Delta Dec 5264 +0.5s -16" 5292 -0.1s +1'08" 5328 -1.7s +17" 5357 -0.6s +15" 5393 -0.4s +19"

5298 +1.0s -40" if = G039

5298 +26.0s +44" if = G035 5302 +31.3s +1'24"

If we assume that JH saw G035 and made the same 30 second error in the position of N5298 that he did for N5302, then the offset would be

5298 -5.3s +44"

That much larger negative error suggests to me that the "standard" identification is more likely to be correct since there are no other large RA errors in the positions for the five nearby galaxies.

On the other hand, N5298 and N5302 are close enough that JH could have seen both in the same field, and could have made the same mistake for each.

Steve then says, "I've observed both ESO 445-35 and ESO 445-39 and they appear similar in the eyepiece with perhaps ESO 445-39 a bit brighter. I don't understand, though, how he [JH] would picked up one of these galaxies and not the other."

He clearly had problems in this field. He missed the brightest galaxy here (IC 4329), and there are several other galaxies in the cluster that he could have picked up, but didn't. I also did not see anything unusual in his notes about the field, simply descriptions of the nebulae. In contrast, earlier in the same night, he made several comments about the NGC 3308/09/11/etc group in Abell 1060, noting double objects, other objects in the group, and so forth. For the N5298 area, these comments are missing.

So, there are some unresolvable problems here. Perhaps this is a case where he fell asleep at the eyepiece. John Stone, his mechanic and observing assistant, is reported to have commented about this happening several times. There are certainly some bright nebulae and doubles in the south that JH should have swept up, but did not.

Some additional notes: the magnitudes of G035 and G039 are virtually identical (B = 14.0), and the diameters are not too different, either, so I don't see an easy way to use the data to choose between the two. Again, JH could/should have picked up both, but didn't. So, we're stuck with the ambiguity.

In the end, I'm going to put a colon on the N5298 identification, and put G035 in with a question mark.

Historical observations

John Herschel (1847) Cape Observations

Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "F, R, gbM, 30 arcseconds."

Published comments

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 14.0 mag galaxy. Their coded description reads R,DIF,STELNUC.

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