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 Post subject: Comets at Carranza
PostPosted: Sat May 06, 2017 10:26 am 
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The beautiful weather on Wednesday, May 3, was predicted to continue overnight, and on Thursday morning, May 4, the sky was indeed clear, so I headed to the Pines (Carranza Field) to catch the last usefully-long window of full darkness until after the full moon on May 10. The moon set at 2:51 am EDT, and astronomical twilight began at 4:11 am, leaving 80 minutes of darkness.

In particular, I wanted to get another look at comets 41P/Tuttle-Giacobini-Kresak and C/2015 V2 (Johnson), each of which would be high overhead at 3 am. I might also be able to catch C/2015 ER61 (PANSTARRS) low in the east at the start of twilight. In addition, I wanted to take some snapshots to finally test my 7D Mk II camera under dark skies.

I arrived at 2:40 am, and after I put on a winter coat and got out my 16x70 binoculars, I was able to able to spot comets 41P and Johnson with the 16x70s by 2:45 am. 41P was just over 4° from Vega, but wasn’t that obvious because it was less than half a degree from the relative “glare” of magnitude 4.3 Kappa Lyrae. Johnson was near the western foot of Hercules, but had just crossed the border into Boötes. It was a pleasant surprise as it now had a clearly visible coma, unlike the ghostly patch it had been at Carranza on April 19 or Tatem Observatory on April 29 (the latter is in Medford, at the transition of the outer suburbs to the Pines, plus there was an 18% illuminated crescent moon in the sky).

Although there are bands of light pollution visible along the horizon at Carranza (Philadelphia to the northwest, Joint Base McGuire to the north, Toms River to the northeast, Atlantic City to the south and Hammonton to the southwest), the overhead sky was marvelous with obvious Milky Way running from Cepheus through the Summer Triangle then down into Sagittarius. It was nearly at the “billowing” level.

I’ve attached a snapshot of the Summer Triangle. It was taken at 3:05 am with a Canon 7D Mk II digital SLR camera (on a fixed tripod) and a Sigma 20 mm f/1.4 Art lens. It’s a single frame exposed 8 seconds at f/2, ISO 3200, 3600K white balance. A few more snapshots (with mouseover annotations) are on my web page. The camera performed satisfactorily.

Because I was fooling around with the camera, and the window of darkness was short, I just did some casual general observing with the 16x70s. I saw a number of globular clusters (e.g., M5, 13, 92, 22, 28, 4, 80, 56, 71, 10, 12), a couple of planetary nebulae (M27 and 57) and a few galaxies (M31, 51 and 101). My memory breaks down with all the stuff seen with the binos along the Milky Way heading south from Altair. I would also add that the Coathanger and M8 were not difficult to see with unaided eyes.

Finally, at 4:12 am, just after the start of twilight, I gave up looking for Pan-STARRS, which was less than 4° to the right of the Circlet of Pisces, but just under 10° altitude. Unfortunately, although it was quite clear overhead, some cloudy haze had developed along the horizon, which is bad for diffuse objects. However, I was able to spot nearby Neptune (8° to the right of Pan-STARRS’s location, and a few degrees lower), but the magnitude 7.9 planet was only at threshold of visibility in the 16x70s.

I pulled off the field at 4:20 am.


Attachments:
Summer-Triangle_7DII_04-May-2017.JPG
Summer-Triangle_7DII_04-May-2017.JPG [ 124.72 KiB | Viewed 278 times ]

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Joe Stieber
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 Post subject: Re: Comets at Carranza
PostPosted: Sun May 07, 2017 7:40 am 
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That's a very impressive shot of the Summer Triangle. Beautiful and sharp.

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 Post subject: Re: Comets at Carranza
PostPosted: Sun May 07, 2017 3:19 pm 
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Location: Maple Shade, NJ
Thanks Matthew, but I would be inclined to stick with my original evaluation of "satisfactory." My astro-snapshots are hardly works of astrophotographic art. They are more like family/vacation pictures, mementos of an experience; in my case, an observing session.

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