My first "real" light curve

Eamonn - that's very encouraging. The online information on Mira Pro doesn't go into details around NZP's and first/second order extinction. And sure, I think that at this level, anything is going to be complicated...

I've been looking at some alternative methodologies in the literature. Landolt fields are "the standard" but there are shorter options (e.g. using Henden fields). I'm guessing that getting onto the standard (Landolt) system is the best (but not necessarily required) though other methods can get you close enough. I suppose it depends on what you're doing and the nature of the data as to how far you need to go.

By the way, I was flitting around the web and I came across to other sets of standard fields - "Stetson" and "JHK". Any idea where they came from and if they have any use?

Thanks for the information on Mira pro - that's very helpful indeed.

Oh, and that's an excellent scheme for checking sky conditions. I've not seen that before.

Dave

Hi Dave,

I presume you won't be monitoring in the infrared (IR) because if you do you can use the JHK photometric system. JHK was specifically developed for IR bands not the visible.

Regarding the Stetson photometric standard fields, you'll find that the stars are widely spaced as compared to Landolt. Also the stars are in BVRI bands. Although this is no problem, I use Landolt myself when I was carrying out surveys. There are a lot more stars to choose. So I have a personal preference for Landolt stars.

If your planning colour photometry, watch out that the Johnson & Morgan system is being phased out. Although the Bessel and Cousin filters are still around, they also will be phased out. Of course both core types have slight variations in the UBVRI.

The reason for the phasing out of the these filters is because
chips were red peaking at around 0.7 microns. Now there peaking
at around 0.5 microns. This distorts the true photometric response.

Although I use Bessel filters, I have recently used SDSS filters. In time they will be the norm. My CCD camera sensor peaks at 0.7 microns. It's an old camera by todays types.

The reason I'm using SDSS filters is because I have been experimenting with another camera that peaks at 0.5 microns.

The SDSS provides wider bands and therefore more light. It also depends on your chip sensor spectral response and QE. I think your chip could be blue orientated.

Eamonn

www.kingslandobservatory.com

Eamonn - my current filter set (BVRI) are Custom Scientific to Bessel and Cousins specifications. I use a KAF1001E chip. I'll check out its response and see where that lies.

I'll check out the SDSS filters. I guess that if the "norm" is going to change then its better to be prepared.

Thanks for all the info!

Dave Mc,

I wouldn't just rush out now to purchase SDSS filters. Its going to be some years before its a norm. There is a significant amount of astronomers still using and publishing with Bessel & Cousins UBVRI filters.

The reason I am using SDSS filters is for a collaborative project
that I am involved in that specifically requires these filters. SDSS are expensive.

Dave, your Bessel filters from Custom Scientific are the best you can obtain.

Eamonn

www.kingslandobservatory.com

Actually Eamonn - they aere *really* hard to get hold off - I didn't see any of the mainstream supplier offering them though I think I saw Astrodon with them in the catalogue...

Anyhow - good news that I don't need fork out yet more dosh - the Custom Scientific filter set I got was the price of a small APO... But they *are* the bees knees

Dave,

Re SDSS filters, Barr Associates and Omege have them at Rolls Royce prices. Don't go near them, they specially make filters for
all the big observatories. Hubble, Keck to name a few.

I bought SDSS filters from Astrodon. The prices were expensive for the 50mm. so I redesigned the camera nose arrangement to take 29mm. The price came down dramatically and affordable.

Eamonn

www.kingslandobservatory.com