Monday, March 1, 2021

New Comet C/2021 C4 (ATLAS)

CBET 4937 & MPEC 2021-D113, issued on 2021, February 26, announce the discovery of an apparently asteroidal object (magnitude ~19) on CCD images taken on Feb. 12.6 UT with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program. This object has been found to show cometary appearance by CCD astrometrists elsewhere after the object was posted on the Minor Planet Center's PCCP webpage due to its orbit. The new comet has been designated C/2021 C4 (ATLAS).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 5 unfiltered exposures, 90 seconds each, obtained remotely on 2021, February 22.2 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 8" arcsecond in diameter. (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott):


Credit: Minor Planet Center
 

M.P.E.C. 2021-D113, assigns the following preliminary parabolic orbital elements to comet C/2021 C4 (ATLAS): T 2021 Jan. 21.04; e= 1.00; Peri. =  320.80; q = 4.50;  Incl.= 132.85


by Ernesto Guido

Tuesday, February 9, 2021

The Dig & Basil Brown's book on Star Charts

A recently (January 29, 2021) released film on the Netflix streaming platform, The Dig, tells the story of the 1939 excavation of Sutton Hoo, the exacavation of the great 7th-century Anglo-Saxon royal ship burial, considered one of the greatest archaeological discoveries in British history. It is a very interesting scientific and human story that will not fail to interest and attract many viewers. On the internet you can find accurate accounts of the events that occurred in Sutton Hoo and that saw as main protagonists local self-taught archaeologist-excavator Basil Brown and landowner Edith Pretty who hired him to tackle the large burial mounds at her rural estate in Sutton Hoo near Woodbridge. 

Credit: B. Brown

For astronomy enthusiasts like the readers of this blog, one of the most interesting facts is certainly that the protagonist of this story, Basil Brown, was not only an archaeologist but also an amateur astronomer. Brown (22 January 1888 - 12 March 1977) joined the British Astronomical Association on 27 November 1918. Through NASA ADS it is possible to find and read some of his astronomical notes and reports published on the BAA Journal (JBAA). 

For example he observed the transit of Mercury across the Sun on 7th May 1924 at Diss, Norfolk, with his only instrument a 2-inch (50mm) refractor (in the film you'll see Ralph Fiennes as Basil Brown carrying around a small telescope). His report to BAA was illustrated with four sketches: "the foregoing is an interesting illustration of the capability of a small telescope in the hands of an enthusiastic amateur".

He also observed meteors, the aurora and the zodiacal light. Basil was also searching for comets as reported in a Notes section of November 1921 of JBAA: "COMET NOTES. -- I have been glad to hear from Mr. Basil Brown that he has spent a good many hours in sweeping for comets. This should be one of the main objects of the sectional workers, especially when no known comets are within reach".

One of the facts that the viewer learns about while watching the movie The Dig, is that Mr. Brown is the author of an astronomy book, specifically a book on Atlases and Celestial Maps. In fact, while Mr. Brown never published any of his archaeological work, "the good reception which greeted his various astrono-mical papers led him to  publish in 1932 the book "Astronomical Atlases, Maps and Charts" a work which the publishers then described as  'filling an inexplicable gap in the literature'".

As it happens, I own a copy of the first edition of the book published in 1932 by Search Publishing Company in London (a reprint was published in 1966). and I think it's interesting to share here some photos of this beautiful book. (click on each image for a bigger version)

Credit: E. Guido

 

This is a book that should not be missing from the shelf of any fan of the history of astronomy (unfortunately it is quite difficult to find) and in particular of that fascinating branch that is the mapping of celestial things. The book, which as the subtitle says is a historical and general guide, is full of references and anecdotes about atlases, star charts and their authors.  As Mr. Brown points out in his introduction (a part is reproduced in the images below): "History is as essential to science as roots to a tree. Modern Astronomy may be likened to a great city built on foundations dating back so far as to be almost as old as the human race". There are also in the book illustrations of the most famous atlases and maps of antiquity. Some chapters are devoted to the mapping of the Moon, the Planets and the Sun.

 

 

Credit: E. Guido

Credit: E. Guido


There are several pages devoted to maps containing information and locations of comets of antiquity. The author provides a whole series of book titles that will help the comet scholar.


By Ernesto Guido

Friday, February 5, 2021

New Comet C/2021 B3 (NEOWISE)

CBET 4929 & MPEC 2021-C16, issued on 2021, February 04, announce the discovery of a comet (magnitude ~19) in infrared images obtained during Jan. 22 UT with the Near-Earth Object Wide-field Infrared Survey Explorer (or NEOWISE; formerly the WISE earth-orbiting satellite). The new comet has been designated C/2021 B3 (NEOWISE).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 50 unfiltered exposures, 30 seconds each, obtained remotely on 2021, January 27.1 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 10" arcsecond in diameter. (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott):


 

Credit: Minor Planet Center


M.P.E.C. 2021-C16, assigns the following orbital elements to comet C/2021 B3: T 2021 Mar. 11.18; e= 0.93; Peri. =  293.69; q = 2.15;  Incl.= 119.50


by Ernesto Guido

Saturday, January 30, 2021

New Comet C/2021 A1 (Leonard)

CBET 4907 & MPEC 2021-A99, issued on 2021, January 10, announce the discovery of a comet (magnitude ~19.5) by Gregory J. Leonard on CCD images taken on Jan. 3.54-3.56 UT with the Mount Lemmon Survey's 1.5-m reflector. The new comet has been designated C/2021 A1 (Leonard).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 14 unfiltered exposure, 120 seconds each, obtained remotely on 2021, January 6.4 from H06 (iTelescope network, New Mexico) through a 0.43 m f/4.5 Reflector + CCD, shows that this object is a comet with a diffuse coma about 7" in diameter.

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott):


M.P.E.C. 2021-A99, assigns the following nearly parabolic orbital elements to comet C/2021 A1: T 2022 Jan. 3.3; e= 0.99; Peri. =  225.09; q = 0.6;  Incl.= 132.68

This comet has excellent brightness prospects for December 2021. In fact, before the perihelion on January 3, 2022, at a distance of 0.6 AU, comet C/2021 A1 (Leonard) will pass just 0.233 AU from Earth on December 12, 2021 and it will have an exceptionally close pass of Venus at 0.028 AU on December 18, 2021.

Comet C/2021 A1 (Leonard) could potentially become a naked-eye object. Below you can see a graph generated using the software Orbitas and showing the predicted magnitude (in red) versus the maximum height (for Northern Hemisphere). (as always with comets, the future magnitudes reported here are only indicative). 


Below a graph showing the orbit diagram (made using the JPL Small-Body Database Browser) of comet C/2021 A1 (Leonard) and its position on December 18, 2021.


by Adriano Valvasori & Ernesto Guido