Spectrophotometry

[Starlight 1]

I did say I start a new post on photometer So here the start if you would like me to put in more I will.

The Starlight-1 consists of 3 basic parts:

The photometer head which detects light though your telescope and converts it into a useful electrical signal.

The interconnecting cable which carries the ECL signal to the photon counter,and supplies low voltage to the dc-dc power supply in the photometer head

The photo counter and controls the counting and processes the signal into a digital ,TTL,analog,or multiplexed BCD INPUT/OUTPUT FOR COMPUTER INTERFACE.

How do it all works ,Well its in 3 parts again ,Digital: dead time,gate time,unit count,accuracy.

Analog range,response,linearity,dead time.

TTL:input/output BCD-1,BCD-2,BCD-4, BCD-8 This is start ,stop,reset,control,ground.

[jsandse]

Ok I would like to know more and will start with some questions. Forgive me if they are simple but I've never used spectrophotometers before:

1) What advantages has this setup over a sensitive cooled CCD camera?

2) What is the field of view of the spectrophotometer - for instance when I record light from a star in photometry I always want to have a standard reference star in the field of view? - is this posssible with the spectrophotometer

3) What is the sensitivity of this spectrophotometer? eg down to what magnitude of star can we do spectrophotometry on and with what SNR

4) Are these detectors expensive?

cheers

John

[Starlight 1]

I put in more John This take photon counting in nsec.

[Starlight 1]

Part two,

Since the reticle is in side the head you can only use a eyepiece from 10mm to 19mm for focal

The photomultiplier tube is for UBV measurements.and a tube for measurement into the red and near infrared spectral regions,

red response to 8500 0 over A,

Operate temperature range -15 oc to +50 0c

The photomultiplier tubes is a very sensitive device.

It use 25 -pins to carry the data in and out .

The count panel is a 8 digit led display

We work in gate time from 10,1,0.1, or 0.01 seconds

[Starlight 1]

part three.

The head has a flip prism into either the view position or count position

Aperture: work in .020 inch ,.052,.0995, .1495,.250,or set bB .010,.020,.0313,.040,.199

you set this on your choose depends upon the desired field of view, telescope focal length, and telescope tracking accuracy.

[Starlight 1]

Part four

The start and stop pulses are only 1000ns each , it takes 2 milliseconds to read the data so i can work very fast at taking reading.

The u or ultraviolet peaks at 3600a and is approximately 1000a wide, Blue is 4200a x2000a and V is 5400a x2000a

photo counting (pulse counting)techniques to measure the brightness of the light source. so the brighter the star the more photos will strike.

[Starlight 1]

Looking like a uninteresting post to you so Its time to give in as you get no photos at the end of this ,

[nytecam]

Basically then it records very broad wavebands via the filter applied over the sensor - at best about half a dozen wavebands across the visual/NIR region. The crudest spectrometer using prism or grating dispersion will be an order of magnitude superior.

[Starlight 1]

Yes ,But you can add more filters in the unit if you wish to .I was going to do the full report with data reading and graphs ,But it look like no interrest on this post, its a lot of maths to work it out.

[iwatkins]

Not that there is no interest, honest.

But your posts on this thread just seem to be a big stream of numbers and words and acronyms I don't understand.

I would suggest you start with an explanation of what it is, what it does and why to do it in laymens terms.

Cheers

Ian

[Starlight 1]

Not that there is no interest, honest.

But your posts on this thread just seem to be a big stream of numbers and words and acronyms I don't understand.

I would suggest you start with an explanation of what it is, what it does and why to do it in laymens terms.

Cheers

Ian

Photometry, The science of the measurement of light. Magnitude scale used in astronomy .

[iwatkins]

Nice.