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ASAS Photometry Data

WBY's picture
WBY
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Joined: 2010-07-24

Does anyone know what the 5 different magnitudes represent in the ASAS V data? they are all listed as the Same HJD. Are these 4 sequential exposures with the mean time at the HJD shown? Are they from the same camera or different ones. ASAS only has 4 cameras and I don't think they are all pointing at the same patch of sky at the same time. I haven't found a description of the data file (not the catalog) on the ASAS website. If someone knows where it is, pointing me toward it would be a help.

I am trying to understand which of the values I should use (they are all V band) or whether  I should average them when making a light curve from the data.

Example from Data:

HJD MAG_0 MAG_1 MAG_2 MAG_3 MAG_4 MER_0 MER_1 MER_2 MER_3 MER_4 GRADE FRAME FLAG
3886.979 14.015 14.046 14.038 13.982 13.745 0.041 0.027 0.019 0.018 0.019 D 392 0
3889.99 14.066 14.168 14.186 14.142 13.981 0.061 0.053 0.034 0.028 0.025 D 793 0

 Brad Walter, WBY

Different apertures
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Matthew Templeton
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Joined: 2010-03-12

Brad,

ASAS computes the magnitudes using different apertures, with the smallest (MAG_0) being two pixels wide, and the largest being six.  The smallest aperture is appropriate for the faintest stars (V fainter than 12), while the largest is for the brightest stars.

There's a good summary of this on the following page, about half way down:

https://sites.google.com/site/aavsosequenceteam/asas-tutorial

Matthew

ASAS Data
WBY's picture
WBY
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Joined: 2010-07-24

Thanks Matthew.

Just FYI, I've written an
David Benn's picture
David Benn
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Joined: 2010-07-29

Just FYI, I've written an ASAS plugin for VStar and it's currently under test. I hope to make it available next week.

David

Anyone with insights into the
Gustav Holmberg's picture
Gustav Holmberg
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Joined: 2011-10-29

Anyone with insights into the current status of ASAS north and whether the data will become available?

/Gustav, HGUA

ASAS North
WBY's picture
WBY
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Joined: 2010-07-24

Gustav,

 

The only data from ASAS north of which I am aware is about a years worth of data circa 1999, If I recall correctly, for most of the Kepler field.

After that, I haven't seen data or updates on the ASAS website.

 

Brad Walter

ASAS-SN
FRF's picture
FRF
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Joined: 2010-08-09

In the last few weeks a team of scientist started to report some discoveries on ATEL made by the ASAS-SN project. It seems they use a pair of 14cm telescopes located  at Hawaii and found some transient object on the northern sky. For me it seems they have lack of capacity, probably that is the reason why they report their discoveries mostly several deays or even weeks after the discovery images were taken.

I'm afraid comprehansive new ASAS-North or ASAS-SN photometry databases will not likely be published within the near future.

ASAS-North and ASsAS-SiN
FRF's picture
FRF
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Joined: 2010-08-09

It seems ASAS-North observed SN2011dh two years ago: http://www.astro.princeton.edu/~jprieto/ASAS/SN2011dh/

ASAS-SN page on Prieto's website: http://www.astro.princeton.edu/~jprieto/ASAS/

Abstract from the American Astronomical Society, AAS Meeting #220, #432.03   http://adsabs.harvard.edu/abs/2012AAS...22043203S

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484