TV-102 - the planetary nebula hunter!

by Ron Bhanukitsiri


Planetary in Orphiucus. Seeing was unusually steady and sky magnitude is 5 or better. Observation was between 10:00pm to 11:30pm PDT time.

60x: 30mm Ultima + 2X Ultima Barlow, 110x: 8mm TV Radian
146x: 6mm TV Radian, 176x: 5mm Tak LE, 220x: 4mm TV Radian
293x: 3mm TV Radian, 352x: 5mm Tak LE + 2X Ultima Barlow

First target was the 8.1 magnitude NGC 6572 (the Blue Racketball). This object has been eluding me for about one month now because I was using freebie charts. Tonight with a paid-for The Sky chart, it was still tough to locate by star hopping, being so tiny. At 60x, it still looked like a star. At 110x, the nearby stars are all dimmer, expect the PN. It has blue-green color and still looked like a lightly bloated star that can't come to focus. At 146x (still blue-green), better view and definitely a PN. The 60 degree FOV of the Radian allowed me to see the PN as a ball and the stars to east forming a racket (5 stars forms a racket and 3 stars form racket's handle – SAO123243, GSC443:638, 443:1000, 443:2045, 443:1596, 4432072, 443:2888). Got impression of brighter center. At 176x, 220x and 293x, the PN retained its brightness. Oval shape was detected at 293x and 352x. At 293x, 4 stars form a square (part of the racket) to the east and fit the FOV! Overall, the size of the PN is like that of Uranus. Much brighter than M57!

Next tough one was 11.5 magnitude NGC 6309 (the Box Nebula). This one is easier to star hop and much larger than NCG 6572, but a heck of lot dimmer. At 110x, it's exposed as elongated dim smudge. PN was brighter than the 12.9 magnitude star GSC5652:1465 that forms part of a square to the west of the nebula. At 146x, the PN looked like 2 dim stars inside the PN. At 175x , the PN looks dimmer now. At 220x, much dimmer, 1 (12.1 magnitude GSC5653:201) star now clearly seen outside nebula to the north.

This observation illustrates the usefullness of the Radian's 60 degree AFOV.

It also raise a question about the 4" limiting magnitude of 12.0 which I prosed a questions in Talking Telescopes and Refractor eGroup.