8474 RETTIG binary system discovery

Minor Planet 8474 Rettig from Roger Groom on Vimeo.

Video sequence of the minor planet 8474 Rettig moving across the night sky.

8474 Rettig - 2015-07-11T10:43 UTC
8474 Rettig – 2015-07-11T10:43 UTC

I often participate in astronomical research by way of providing observations to other amateurs and to professionals. The promise is always there of credit for the observations but rarely has it actually eventuate in to anything published with my name on it. Here’s one from recently I’m happy to be involved in and credited for my participation (which was a small but useful contribution):

See it on CBAT

Electronic Telegram No. 4122
Central Bureau for Astronomical Telegrams
CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network
(8474) RETTIG
V. Chiorny, Kharkiv Observatory; V. Benishek, Belgrade Astronomical
Observatory, Serbia; P. Pravec and P. Kusnirak, Ondrejov Observatory;
Yu. N. Krugly, Kharkiv Observatory; J. Oey and R. Groom, Blue Mountains
Observatory, Leura, NSW, Australia; V. Reddy, Planetary Science Institute;
D. Pray, Sugarloaf Mountain Observatory, South Deerfield, MA, U.S.A.;
W. Cooney and J. Gross, Sonoita Research Observatory, Sonoita, AZ, U.S.A.;
D. Terrell, Southwest Research Institute; R. Inasaridze, V. Ayvazian and
V. Zhuzhanidze, Abastumani Observatory; R. Montaigut and A. Leroy, OPERA
Observatory, France; and I. Molotov, Keldysh Institute of Applied
Mathematics, Moscow, report that photometric observations obtained during
May 19-July 23 reveal that minor planet (8474) is a binary system with an
orbital period of 30.54 +/- 0.01 hr. Mutual eclipse/occultation events
that are 0.60- to 0.93-magnitude deep indicate a lower limit on the
secondary-to-primary mean-diameter ratio of 0.86. Rotations of the
components appear to be synchronous with the orbital motion and an
amplitude of the combined primary plus secondary rotational lightcurve is
0.34 mag at solar phases 7-15 deg.

NOTE: These ‘Central Bureau Electronic Telegrams’ are sometimes
superseded by text appearing later in the printed IAU Circulars.

(C) Copyright 2015 CBAT
2015 July 26 (CBET 4122) Daniel W. E. Green

Lake Ballard

Lake Ballard is a salt lake in the Goldfields region of Western Australia. The salt lake is home to an art installation by Antony Gormley know as Inside Australia. This combination of remote salt lake, sculptures and interesting landforms makes Lake Ballard a popular destination for photographers, amateur astronomers, astrophotographers and those simply interested in camping.

Camping facilities at the site are basic but present – long drop toilet, water tank and parking areas where tents and caravans can be set up.

I have been to Lake Ballard on two occasions and both have shown very different sides to what Lake Ballard can be. On the first the salt lake was quite dry and crusty, with a thick white crust which was quite easy to walk on. The second visit over two years later was much wetter, with no solid salt crust and only mud which was very problematic to walk in. You never know quite what you will find when you arrive and exactly what condition the lake and surrounding area will be in.

Lake Ballard
Lake Ballard

Love these tufty little plants around the edge of salt lakes like Lake Ballard in Western Australia. At different times of year their colours can be so varied and vibrant.

Lake Ballard White Wonderland
Lake Ballard White Wonderland


Lake Ballard Salt Crust
Lake Ballard Salt Crust

Dinner at Lake Leschenaultia

Lake Leschenaultia
Lake Leschenaultia. This photograph would make an absolutely beautiful large wall print. Perhaps a high gloss acrylic or aluminium print.


The other night we took fish & chips to the local Lake Leschenaultia, to watch the sunset and enjoy the peace and quiet. It’s pure serenity at the lake late in the afternoon and evening when the crowds have gone home but the gates are still open. The wildlife is incredibly active – birds, tortoise, fish, frogs. Fascinating to watch the goings-n. The photographs above show the nice twilight colours over Lake Leschenaultia after the sun had set, together with some of the water birds. If you look closely you will see dragonfly and disturbances in the water surface from tortoise. For more Lake Leschenaultia photography (available as canvas and art prints if you wish) see a small selection of my work here.

NGC 1600 and Friends

NGC 1600 and other galaxies. 5 x 180 second exposures. 0.84"/pixel scale.
NGC 1600 and other galaxies. 5 x 180 second exposures. 0.84″/pixel scale.

I’ve had some fun reading about this galaxy NGC 1600 and annotating the above photograph with information. This image is from my standard nightly survey of galaxies and as such is only a brief 5 exposures each of 180 seconds in length. I hope you enjoy the representation with additional information about NGC 1600. Some of the information was gleaned from this interesting article on NGC 1600 by Smith. et al 2008.

Below is the plain image without annotations where you can see the galaxies more clearly perhaps:

NGC 1600 and other galaxies. 5 x 180 second exposures. 0.84"/pixel scale.
NGC 1600 and other galaxies. 5 x 180 second exposures. 0.84″/pixel scale.

Karri Forest – Tree

Karri Forest - South-west Western Australia (Pemberton).
Karri Forest – South-west Western Australia (Pemberton).

Looking through my Karri Forest gallery you will probably find very similar photographs to this from 8 odd years ago, probably taken with film! But the fact is I never tire of this kind of Karri Forest photograph, and never tire of the Karri Forest its self. The dripping wet, smell of the rich muddy dirt and composting leaf litter, sound of light rain in the canopy, and a world of amazing photographs everywhere you look.