This repository presents the photometric analysis of the planetary nebula M57 (NGC 6720) using data obtained from the 1.88-m Kottamia Astronomical Observatory (KAO) with the Kottamia Faint Imaging Spectro-Polarimeter (KFISP). The study focuses on the central star’s brightness and the nebular structure in multiple bands.
Observations were carried out using the 1.88-m KAO telescope equipped with a KFISP CCD camera. The main specifications are as follows:
| Parameter | Value |
|---|---|
| Telescope | 1.88-m KAO |
| CCD Model | E2V 42-40 2K CCD |
| Pixel Scale | 0.24 arcsec/pixel |
| Field of View | 8.2 × 8.2 arcmin² |
| Filters | UBVRI + SDSS-ugriz |
The data were reduced following standard photometric procedures:
Bias and Flat-field correction → Cosmic Ray Removal → Astrometric Calibration → Aperture Photometry
Raw and reduced V filter frames of M57 are shown to demonstrate the effectiveness of the data reduction pipeline.
Figure 1: (a) Raw V filter frame of M57 before data reduction. (b) Same frame after reduction and cosmic ray removal.
The reduced V-band frame is displayed in two coordinate systems:
Figure 2: (a) The frame shown in the native pixel scale, highlighting the nebular structure in detector coordinates.
(b) The same frame in the sky coordinate.
The brightness measurements for M57’s central star in different filters are provided below:
| Date | Filter | Magnitude (m ± σ) |
|---|---|---|
| 20 April 2024 (JD 2460420.5) | B | 15.07 ± 0.02 |
| V | 15.66 ± 0.03 | |
| R | 15.81 ± 0.02 |
The target star (central star) and comparison stars used for photometric calibration are marked.
Figure 3: The central star (red) and comparison star (yellow) used for calibration.
Observations in multiple bands provide insight into the nebular structure.
Figure 4: M57 observed in various photometric bands:
(a) B, (b) V, (c) R, (d) I, (e) Hα, (f) OIII.
