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ASAS Photometry Data

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WBY
WBY's picture
ASAS Photometry Data

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

Matthew Templeton
Different apertures

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

WBY
WBY's picture
ASAS Data

Thanks Matthew.

David Benn
David Benn's picture
Just FYI, I've written an

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

Gustav Holmberg
Anyone with insights into the

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

/Gustav, HGUA

WBY
WBY's picture
ASAS North

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

FRF
FRF's picture
ASAS-SN

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.

FRF
FRF's picture
ASAS-North and ASsAS-SiN

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

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