GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- VLT spectrum of GRB990510
- GRB 990510: Broad Band Break
- GRB 990510: BATSE Observations
- GRB990510: optical observation
- GRB 990510 Optical Observations
- GRB 990510, BVI photometry
- GRB 990510 optical observations
- GRB 990510: BeppoSAX/GRBM observations
- GRB990510 optical observations
- GRB990510
- GRB 990510 optical observations
- GRB 990510 optical observations
- Galactic extinction towards GRB 990510
- GRB990510: NFI X-ray source
- GRB 990510 optical observations
- IPN localization of GRB990510
- GRB 990506 Radio Observations
- GRB 990123, optical monitoring
- GRB 990506: BATSE Observations
- GRB 990506, optical observations
- GRB 990510: Final BeppoSAX-WFC Coordinates
- GRB 990506, Optical Observations
- GRB 990506 optical observations
- GRB 990506 optical observations
- GRB 990506, optical observations
- GRB990506 observation plan
- Refined IPN error box for GRB990506
- GRB 990506: Limits on the possible optical transient
- GRB 990506, armchair astronomy
- GRB 990506, optical observations from +1 to +3 hours
- GRB 990506, optical observations
- GRB990506 Optical observations
- GRB990506 observation plan
- New IPN/RXTE error box for GRB990506
- IPN localization for GRB990506
- GRB 970228: Redshift and properties of the host galaxy
- IPN localization of GRB990427
- GRB981220 VLBA observations
- GRB980425 Optical observations of exponential decline at late time
- GRB990321 REFINED IPN ANNULUS
- GRB990323 PRECISE IPN POSITION
- GRB990321 IPN TRIANGULATION
- GRB 990316 Optical Observations
- GRB 990316, Radio observations
- GRB 990316, Optical observations
- GRB990316, Optical observations
- GRB 990316 optical observations
- GRB990316: simultaneous optical observation
- GRB990316 - Optical null results
- ASM/IPN error box for GRB 990308 (BATSE #7457)
- GRB990308 not a new SGR
- GRB 990308a and GRB 990308b
- GRB990308 (Trig. 7457), optical observations
- GRB990308, Possible new SGR~0209+70
- GRB981220, IPN localization
- GRB 981220, radio observations
- GRB 990123, Field Photometry
- GRB 990217 Optical Observations
- GRB 990217, radio observations
- BATSE Resumes Normal Operations
- BATSE Flight Anomaly
- GRB990217: BeppoSAX/GRBM data
- Optical Observations of GRB990217
- GRB990123: Caltech STIS Photometry and Images
- GRB990123 observations
- GRB990217 Optical observation
- GRB990217, WFC position
- GRB990123, Optical Observation
- GRB 990123: Discovery of the Probable Host Galaxy
- GRB 990123: Reduced HST Images
- For Immediate Posting to GCN - HST Data GRB 990123 Available
- GRB19990123 observations
- GRB 990123: BVRI standards in the field
- GRB 990123: Updated Keck Spectroscopy Results
- GRB981220, field photometry
- GRB 990123 NOT Spectrum Update
- GRB990123, Optical observation
- GRB990123, is the "radio flare" due to an inhomogeneous medium?
- GRB 990123: Publicly available reduced HST images
- GRB990123, Upcoming HST Service Observations
- GRB990123, 15-GHz limits
- GRB 990123: New Constraints on Possible Foreground Galaxies
- GRB990123 Optical Observations
- GRB990123, Probability of gravitational lensing
- GRB 990123: Detection of the IR Transient, and the Light Curve Fits
- GRB 990123: Continued Radio Observations
- GRB990123, Preliminary Lens Search Results
- GRB 990123: Correction to GCN 230 - C.A. Young added to author list
- On the Lensing Interpretation of GRB 990123
- Search for Potential Images of GRB 990123
- Search for Potential Images of GRB 990123
- GRB990123, Optical BVRI Observations
- GRB 990123: near-infrared observations.
- GRB990123, OSSE observations
- GRB 990123: Strong MeV CGRO-COMPTEL detection now posted on WWW
- GRB990123: NIR Observation
- GRB990123, ASCA X-ray observation of afterglow
- "GRB 990123: New BV Observations"
- GRB 990123 Optical Follow-Up
- GRB 990123; Addendum to GCN 223