Bro Kayzack,

Saya sokong usaha yang dijalankan ini. Mudah-mudahan ahli-ahli lain ambil manfaat dan jadikan ruangan ini sebagai medan perkongsian dan menyuburkan ilmu.

Agak-agak berapa ramai yang ada CCD kamera untuk buat imaging? Saya sendiri tak pernah guna pasal tak ada... 

BTW, ada ambil gambar komet Tuttle tak dari Langkawi? Sini cuaca belah malam tak ok...

Tak ramai rasanya yang ada dedicated CCD imaging device kat Msia melainkan professional body atau hardcore amatuer. Satu faktor adalah harga. Macam SBIG is way beyond my financial reach 
Tapi DSLR pun boleh dikira CCD device jugak kan, pasal guna CCD chip (walaupun canon punya DSLR guna CMOS) malahan webcam pun sekarang banyak yg guna CCD chip.

ps: Kayzack dari balai cerap Langkawi ker? Dibuka untuk public tak?

aheemm..(OT)

kalau boleh matching dgn promosi airasia dari RM 9.99 up to say RM30 apa kata shan n botok kita pi jumpa saudara Kayzack dan bermalam disana. Saudara Kayzack boleh tak dan berapa orgn sekali boleh muat...weekend boleh tak atau hari2 kerja saje.

Kalau boleh kita akan mohon la.

cheers

CALIBRATION OF CCD IMAGES

Calibration (or PRE-PROCESSING) of an astronomical CCD deep-sky image consists of removing the bias and thermal contribution (DARK FRAME) and dividing the resultant image by the FLAT-FIELD in order to standardize the response of each image pixel.

Calibrated = (Raw - Bias - Thermal) / Flat = (Raw - Dark) / Flat

The DARK frame should be removed firstly from the RAW image then the result should be divided by the FLAT-FIELD.

DARK FRAME

A dark frame is an integration in which no light strikes the CCD. It records the BIAS noise and THERMAL noise for a specific CCD temperature and integration time:

DARK FRAME = BIAS FRAME + THERMAL FRAME

To take a dark frame you can simply cap your telescope and integrate using the same time that you are using for acquiring the raw image. If you are not able to control the chip temperature (+/- 0.1 °C), dark frames should be taken immediately before or after taking a raw image.

For better results shoot lots of dark frames and MEDIAN SUM them.

BIAS FRAME

The bias frame is an image made with an integration of zero seconds and shutter closed. It contains the amplifier zero-point offset, the random readout noise from the amplifier and the noise from camera electronics.

CCD cameras made for scientific imaging usually include the ability to read out a bias frame but for the simple purpose of subtracting THERMAL FRAME and BIAS, a DARK FRAME serves equally well (DARK FRAME = BIAS + THERMAL FRAME). The examination of a bias frame tells you if your camera is working properly: if you see wavy lines or patterns, your camera may not be functioning well.

FLAT-FIELD

The FLAT-FIELD frame is a photosite-by-photosite map of a CCD's sensitivity to light. It is an image of a uniform object such as twilight sky or a sheet of opal glass attached to the inside of the observatory dome. Chip sensitivity, vignetting and dust all appear as variations in the sensitivity of the CCD itself: division by FLAT-FIELD will remove these defects.

When you make a raw FLAT-FIELD, then you must subtract the THERMAL and the BIAS frame from it (or the DARK). For the lowest possible noise, MEDIAN SUM more then one FLAT-FIELD to obtain a Master Flat-Field.



Three different methods of calibration can be used:

Basic calibration - requires a master dark with the same integration time as the raw image;
Standard calibration – requires a master dark that has the same integration time as the raw image and a master flat;
Advanced calibration – requires a master flat, a master dark (same or longer integration time) and a master bias.
Basic calibration is adequate for simple observing tasks. Standard calibration corrects for vignetting and CCD nonuniformity, but constrains you to the same integration timr for your images and darks. Advanced calibration gives you the freedom to use different integration times for your images and provides superior dark subtraction via dark-frame matching.

Oleh kerana CCD camera mahal Sebab tu lah  Balaicerap Negara ditubuhkan supaya mereka yang berminat untuk melakukan CCD imaging tetapi tidak berkemampuan untuk membelinya dapat menggunakannya.  Oleh yg demikian bersegeralah memohon untuk menggunakan balaicerap negara langkawi sambil2 bersantai.

Philips SPC900NC, adik beradik Toucam Pro memang menarik. Dekat Msia boleh dapat dalam harga RM290.00

Cadangan Abg Aziz dan nsyahron tu menarik juga, kalau kita ramai2 sesiapa yang berminat melawat Balai Cerap Kebangsaan Langkawi tu. Saya pernah lalu sahaja tapi tak naik atas bukit tu. Saya di Alor Star memang dah dekat, tapi bab masa pulak yang menjadi halangan, maklumlah 2 alam

Kayzack: Kalau terus pi kesana untuk terus buat imaging saya rasa saperti perpatah melayu saperti rusa masuk kampung la. Taada ke  online tutorial  untuk panduan.

I am interested in the on-site mode. That will give us the reason to bersantai in Langkawi

Although the scopes operation is almost fully automatic and presumably idiot proof but   the first  time you use the system I am sure I need help to get  through the few settings that I might need to be familiar with.
Would the telescope be polar aligned. Is the guide star set by you for say if I type in M42 to target M42.  Do I have make my own dark files, flats and bias frames and how many do I have to take to optimise for your set up.

How about dew. How about clouds. How about exposures and ISO guides. How about focussing; do you take care of it  . Do I have to take a few trial shots. How do I take away the files after imaging. Do I bring a portable H/D or CDR.

So many I am sure FAQ's.

cheers