A Full Night at Kaʻohe

A last star party of the year, actually the last star party of the decade.

'Scopes in the Twilight
A pair of 8″ telescopes in the twilight, with a setting Moon and Venus over Hualalai

With new Moon in the middle of Christmas week I had the choice of the weekend before Christmas, or the weekend after. Guessing that attendance would be better in the quiet days between holidays I chose December 28th as our monthly new Moon star party.

The site was, as usual our Ka’ohe observing site on the side of Mauna Kea. The weather was nearly ideal, clear, not very cold, and almost no wind at the site.

Arriving at the site to find beautiful, clear skies we marveled at the sunset scene. A brilliant Venus and three day old crescent Moon hung above the fading sunset and Hualālai.

Orion with a faint Betelgeuse changing the appearance of this familiar constellation
Orion with a faint Betelgeuse changing the appearance of this familiar constellation

One of the spectacles of the night was Betelgeuse, normally the 11th brightest star in the sky this red giant has suddenly faded to half its usual brilliance. Normally about 0.5 magnitude the star has faded to about 1.4 and continues to dim. The fading star has left this iconic constellation looking somewhat distorted to those who know it well.

I had brought out my big ‘scope, my 18″ Deep Violet. I had spent a few hours earlier in the day preparing this somewhat neglected telescope, realizing that I had not user her very much through the year. The plan was to use the big ‘scope to observe comet C/2019 Q4 Borisov, the interstellar visitor.

The evening started with views of old favorites, sharing the eyepiece with new folks and visitors. The Double Cluster, Andromeda, I had to wait a while for Orion to rise out of the trees.

My personal observing plan was to work on galaxies in Eridanus, just west of Orion. This field would be well placed through much of the night, transiting mid evening and near zenith. Ideal conditions to hunt faint fuzzies.

NGC1547 Small, round, faint, modest core

NGC1575 Small, round, faint, stellar core

NGC1498 A triangle of faint stars a couple arcminues across, at low power it appears as a faint fuzzy galaxy, a little magnification betrays its real nature as a mere asterism.

NGC1594 Small, elongated 2′ x 1′ east-west, no notable core

One by one the others left… Cliff, then Jim were the last to leave. I had the night to myself. With Violet setup and operating nicely I had no reason to cut this night short. I was still warm and I still had munchies left, on to the next galaxy.

NGC1600 Good sized, bright, round, bright core, NGC1601 on the northern margin, a rough line of 11-12 magnitude stars about 2′ west running north to south

NGC1602 Small, bright, stellar core, on the northern margin of NGC1600

NGC1611 Small, elongated 1′ x 0.5′ east-west, no notable core, center of a group of four with NGC1609 to the southwest, NGC1612 and NGC1613 to the northeast

Deep Violet and Meteor at Kaʻohe
My 18″ Deep Violet set up at Kaʻohe with a lucky meteor in the background

In the long hours after midnight I left the galaxies of Eridanus to wander the sky. I stopped by old favorites… R Leporis, The Owl, the Auriga Clusters, The Whirlpool, The Antennae. I wandered some small galaxies in Ursa Major and Lynx.

What breeze had been there early in the night faded, leaving a dead calm. I could hear the wind high on the shoulder of the mauna above me, while around me the dew returned. In the grass down slope a pig snorted and rooted around for a bit, my only visitor in the night.

NGC3717 Bright, elongated 5′ x 2′ northeast-southwest, a 12th magnitude star northeast of the center

IC2913 Small, round, no notable core

PGC32921 Small, round, very faint, modest core

NGC2537 Round, bright, an odd bright patch on the southern edge, no core, about 1′ across, a 12th magnitude star 2′ southeast, IC2233 visible 16′ south

IC2233 Fair sized, elongated 2′ x 0.5’north-south, faint, no core visible, no dust lane visible, a faint slash of light, a 10th magnitude star 2′ east, a 13th magnitude star in the north end of the disk

Checking on the position of Comet Borisov I make my first attempt to locate it around 3am. It is still a bit low for a 15th magnitude object, but I find I can make out any number of stars at 14.7 and fainter in the field. Earlier in the evening I had located and observed several 15th magnitude galaxies, it should be in reach when it gets higher. The trick was to find one faint dot that moved among the stars.

As the field rose I could make out fainter stars, but still nothing moved. I checked the GAIA stars in the field and noted I eventually made out stars as faint as 15.9 magnitude.

I spent well over an hour attempting to find one very faint moving dot, one just at the limit of my equipment and eyesight. At one point I thought I had it, then checked again over the next twenty minutes to find the object had not moved, just a very faint star.

I never did locate it despite a serious effort.

It was not until writing this post the next day that I discovered the issue… No thanks to Sky Safari I was looking in the wrong place. Not by much, about 15 minutes of arc, or about a quarter degree away.

I found this by comparing the coordinates from the JPL Horizons
ephemeris
 , the gold standard in position calculations, to those given me by Sky Safari. At 4am the coordinates from Horizons were 12h02’02.73″ -34°19’18.3″ while Sky Safari gave me 12h03’03.49″ -34° 25’52.4″. The comet was probably in the field of my low power eyepiece, but when looking at the faintest objects in the field I missed it.

I am not very happy about that.

Ski Safari is the best tablet planetarium software, they claim arcsecond accuracy on position calculations for solar system bodies. I expect I will be sending their customer service a message.

While I had expected to stay well after midnight, I did not expect to stay until the glow of dawn lit the sky. With the east brightening I put away the telescope and drove home, but not before one last look at the fading stars overhead.

Author: Andrew

An electrical engineer, amateur astronomer, and diver, living and working on Mauna Kea, Hawai'i.

One thought on “A Full Night at Kaʻohe”

  1. Great report Andrew. The vis was a bust with now an extra bright lampost at its parking lot.
    And windy.
    Aloha

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