New webpages on AL3, Whiting1

New partly preliminary webpages have been added to the SEDS MWGC website for the following new globulars:


Whiting 1:

2 thoughts on “New webpages on AL3, Whiting1

  1. Les Dalrymple

    I am happy to report a threshold visual detection of the new globular cluster AL 3 in Sagittarius that was confirmed by two other observers at 10.00 hrs UT on 22 July 2006.

    I was very fortunate to have unusually good conditions at my Bargo site (150km SW of Sydney, Australia) with a ZLM about 6.4-6.5 and very good to excellent seeing that allowed very high magnifications to be successfully employed while retaining good , near pinpoint star images.

    The field was located using Megastar and a 15′ x 15′ POSS II red plate using a 46cm f/4.9 Newtonian with 7mm Nagler + Ultima 2x barlow yielding x634 and a 7.5 arc-min true field. The cluster was found to be almost due north of SAO 186501 (mag 8.85) by 3.5 arc-mins, and is almost pointed at by GSC 6855:724 and GSC 6855:336 at mags 11 & 12 respectively.

    It appeared as no more than the weakest gossamer glow — seeming little more than a field surface brightness irregularity/enhancement, with a couple of threshold mag stars (approx mag 16.5 – 16.8) region sewn over. Appears less than 1′ diameter — certainly very, very much more difficult than DJ-2 and NGC 6540 (with which it was compared in other ways in the discovery paper). Somewhat comparable to some of the nastier examples of the small Terzan clusters (Terzan 4 and Terzan 9 come to mind). Not seen or even suspected at x185 or x247. Suspected but doubtful at x317. At threshold at x 636. The Vt supplied at 11.0 +/- 0.4 seems a long way off the mark — seems more like early or mid 15s.

    I beleive I may be the first person on the planet to _visually_ observe this object — which for a G.C afficianado like myself was a great thrill.

    Les Dalrymple
    Contributing Editor S&T Magazine


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