Sunday, July 15, 2007

Difficult time with Comet C/2006 V13 (LINEAR)

Session name: 20070714.2200

I have not seen Comet C/2006 V13 (LINEAR) yet.

Contrasting with a positive weather forecast, our urban dome was veiled with strips of cirrus and glossed with a haze. This session's's horizon, too, had a pinkish-brown hue, strong in manhattan-south-southwest. Yet, believing that persistence yields results, I arrived at TotL around 10PM EDT to find Hannah, Ken T., and Tom C. sitting on the park bench. Tom's 16x70 bins pointed in the direction of Jupiter.

I traveled with the light pack - two bins and a Bogen tripod outfitted with the Bogen 410 head. This was going to be a quick session. No sidewalk astronomy. Locate and observe the comet - that was plan. Complete the night with a naked eye tour of the sky. Our previous session was a clear night where the constellations Aquila and Sagittarius stood brightly above our eastern tree line. The tree to our east partially blocked Capricorn east of Sagittarius. Brightness-deficient Delphinus and Sagitta were high in the sky east of Aquila. Charlie and I glimpsed naked eye the faint shimmering of the handle stars of the Coathanger (CR399). I wanted to continue this tour this session. My desire was stronger than what I knew to be true.

The section of walk where the three were sitting, TotL-east, benefits from a coniferous tree that embraces one of the lampposts. A red towel, used for wrapping the bins while traveling, was re-purposed as a lamp shield for the other lamppost. Darkness wonderfully lit our little corner.

I set up my bins near Tom but trained the glass high up towards the northwest on Alkaid, eta UMa. In the 2* field of view the starhop was going to be easy. Two fields of view almost directly in altitude landed on a bright scalene triangle made up from kappa^2-, iota-, and theta Boo. Another pan in altitude, a little bit better than a field of view brought in square-shaped gathering of stars I used for a landmark. The ephemeris I have on hand, MPC 60097, places the comet between that square and a magnitude 6.5 star (HIP 72508) at the top of the field of view. I don't see it. Tom scanned the area in his bins and couldn't see it. A feeling of deprivation.

Tom was describing how this magnitude 8 comet was at its closest approach to earth in some enormous amount of time. Our skies can't be that bad for this comet. I stared into the eyepieces at the field of view. More stars began to resolve the longer I looked. My best guess is that I saw as dim as magnitude 9.3. If the comet is magnitude 8 or dimmer and has area then it may be too dim for these bins. The comet could fall below the contrast threshold where we just can't see it. (The other night had the 4" Tak in this area with no success.)

Friday, July 13, 2007

Manhattanhenge July 2007

Session name: 20070712.1945

The second occurrence of Manhattanhenge is Friday the Thirteenth, 13 July 2007 when the event begins approximately 8:20PM EDT and the sunsets 8:27PM EDT. The weather forecast for this date had not been promising so I took advantage of the clear skies this day.

In the past I have observed Manhattanhenge with throngs of others at 34th & Park Ave. Along the sidewalks we wait for the light to change red and rush for the yellow centerline, jockeying for the best position. Those in the foreground obscure our view of the horizon and soil the photo opportunity. This year I observed both events from Summit Rock in Central Park where I can set up unencumbered without any obstacles and remain stationary for the entire event. Two other folks observed sunset from the hillock behind me.

Sunset was too bright for the naked eye - a "painful" brilliance. I watched the entire sunset through the homemade solar paddle and on the small LCD of the camera.

A Manhattanhenge movie created from a series of digital stills taken on 12 July 2007 around 8:15pm with a Nikon Coolpix 995 from Summit Rock in Central Park (map). The view is looking west over the valley of 83rd St into the Palisades of New Jersey across the Hudson River. The duration from when the Sun first breaks the building to sunset is approximately 11 minutes 30 seconds. (Haven't calibrated the camera's clock with actual time.)

After the Sun set, I observed the horizon with handheld 7x50 binoculars. A low hanging cloud caught my attention where the upper rim glowed neon orange-red. It is pictured below and this was a first for me. I don't know the proper term for this atmospheric phenomenon.

Want to to receive alerts about this, as well as other AMNH and astronomy-related news? Subscribe to star-struck.

Want to learn more details. Astrophysicist Dr. Neil deGrasse Tyson, Director of the American Museum of Natural History's Hayden Planetarium, describes the circumstances of this NYC phenomenon in a few places. Check out the following to get started.

Nova scienceNow : Manhattanhenge videocast

American Museum of Natural History: Manhattan-henge (star-struck article)