Welcome to Astrosite Groningen. On these pages you mainly find information, and a presentation of results, on a number of astronomical subjects that we find most interesting. Our main interests are comets and variable stars; therefore, emphasis will be on the various aspects of observing these objects (charts, observations, photographs). But we also plan to cover other topics, albeit only as an aside, such as eclipses, and atmospheric phenomena like aurora and noctilucent clouds, mainly by presenting a selection of our photographic results. We hope you enjoy this site. We always welcome comments, and suggestions for improvement. And feel free to contribute: observations, images, whatever you want to share... Reinder J. Bouma Edwin van Dijk

Minor planet 9706 on August 17, 2002 in NEAT images.

Recent updates (over the last month)
Sep. 26, Observations of C/2017 K2, C/2020 K1, P/2022 P1, 22P, 73P and 327P.
Sep. 24, Observations of C/2017 K2, C/2020 K1, C/2020 V2, C/2022 E3, P/2022 P1, 22P, 73P and 117P.
Sep. 19, Observations of C/2017 K2, C/2020 K1, C/2022 E3, P/2022 P1 and 73P.
Sep.  9, New APASS file for September/October. New charts for C/2017 K2.
Sep.  5, Observations of C/2017 K2, C/2020 K1, C/2020 V2, C/2022 E3, P/2022 P1, 22P and A/2100.
Aug. 28, Observations of C/2017 K2, C/2020 K1, C/2020 V2 and C/2021 E3.


SQM-L sky brightness measurements at our observing sites. Click here.


Visually observable comets
Comet
Mv
Trend
Charts
covered by APASS file
C/2017 K2 (PANSTARRS)
8-9
brightening
yes
no
C/2019 L3 (ATLAS)
12-13
fading
no
yes
C/2020 K1 (PANSTARRS)
13-14
near maximum
no
yes
C/2020 R7 (ATLAS)
13-14
fading
no
yes
C/2020 V2 (ZTF)
12
brightening
no
yes
C/2020 Y2 (ATLAS)
14-15
near maximum
no
yes
C/2021 E3 (ZTF)
12-13
fading
no
yes
C/2022 E3 (ZTF)
11-12
brightening
no
yes
P/2022 P1 (NEOWISE)
10-11
brightening
no
yes
22P/Kopff
14
fading
no
yes
29P/Schwassmann-Wachmann 1
-
regular outbursts
no
yes
73P/Schwassmann-Wachmann 3
12-13
fading
no
yes
81P/Wild 2
13-14
brightening
no
yes
117P/Helin-Roman-Alu 1
14
fading
no
yes
118P/Shoemaker-Levy 4
13-14
brightening
no
yes
327P/Van Ness
14-15
near maximum
no
yes

NEW! September 9, an updated file with comparison stars from APASS in the magnitude 10-15 range is available for the September/October
        moonless period.


Comet C/2021 A1 (Leonard) at perihelion

This comet, discovered a year ago as the first one of 2021 is passing perihelion today.
Over the last couple of weeks it has developed into a very fine object in the evening sky, in particular for observers in the southern hemisphere.
It is very active, producing modest brightness outburst every 4 days or so since the middle of december, and showing a spectacular tail in wide
field images, unusual for a comet that never became brighter than about magnitude 3-4 in a dark sky. A good example is the image above which was
taken less than 24 hours from perihelion by Michael Mattiazzo from SWAN Hill, NSW. Currently the comet is about magnitude 5 visually.
It is expected to fade gradually over the coming weeks moving away from both the Earth and the Sun.  [03-01-2022]


Bright comet C/2020 F3 (NEOWISE)!

This comet, discovered on March 27 by the NEOWISE satellite as a magnitude 17 object, brightened to 7th magnitude for southern hemisphere observers
before disappearing in evening twilight en route to perihelion on July 3 at slightly under 0.30 AU from the Sun. In the meantime it had become evident that this
was an 'old' object, and there was good hope that northern hemisphere observers would see a naked eye comet near about magnitude 3 deep in morning twilight shortly
after perihelion. So it was a pleasant surprise that C/2020 F3 actually emerged as a first magnitude object sporting a bright dust tail that rapidly grew longer
and longer over the last week as the comet could be seen higher above the horizon in a darker sky.
The (binned) image to the right was obtained on the early morning of July 12 by Martin Mobberley from Cockfield, Suffolk, UK and is a fair representation
of what visual observers were able to see around the same time.

A full version of this image including observing details can be viewed by clicking here.
Over the coming weeks comet NEOWISE, now placed in the evening sky, will fade fairly rapidly after its closest approach to the Earth - the minimum
distance was 0.692 AU around 23.0 July - moving south and becoming better placed for more southerly observers.







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