Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21791 results found.

  1. GRB260914A: MAO/AZT-22 optical observations
  2. Fermi GRB 260926A: Global MASTER-Net observations report
  3. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  4. GRB 260924A: COLIBRÍ optical observations
  5. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  6. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  7. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  8. GRB 260925A: Swift/UVOT Upper Limits
  9. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  10. GRB 260924A: Optical follow-up observations with Kinder
  11. EP260924a: J-band upper limit with WINTER
  12. EP260924a: EP-WXT detection of an X-ray transient
  13. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  14. GRB 260924A: Swift/UVOT Detection
  15. GRB 260924A: GROWTH-India Telescope optical observations
  16. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  17. GRB 260924A: NOT optical counterpart confirmation
  18. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  19. Fermi GRB 260923A: Global MASTER-Net observations report
  20. Trigger_21914: Swift ToO observations
  21. EP260806a: e-MERLIN detection at 5 GHz
  22. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  23. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  24. ATCA observations of GRB 260909A
  25. GRB 260922A: J-band upper limit with WINTER
  26. GRB 260922A: Swift/UVOT Upper Limits
  27. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  28. GRB 260918A: SVOM/ECLAIRs refined analysis
  29. GRB 260922A: SVOM/C-GFT optical upper limit
  30. GRB 260921A: Fermi GBM Observation
  31. EP Alert 260921.58: Global MASTER-Net observations report
  32. GRB 260917B:: SVOM/ECLAIRs refined analysis
  33. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  34. Swift GRB 260921A: Global MASTER-Net observations report
  35. GRB 260921A: Swift detection of a burst
  36. EP260920b: LCO observations
  37. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  38. EP260920b: COLIBRÍ optical observations
  39. EP Alert 260921.01: Global MASTER-Net observations report
  40. EP260920b: Global MASTER-Net observations report
  41. EP Alert 260920.66: Global MASTER-Net observations report
  42. EP260920a: NOT early time optical upper limits
  43. EP260917a: Global MASTER-Net observations report
  44. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  45. IceCube Alert 260919A: Global MASTER-Net observations report
  46. EP Alert 260919.40: Global MASTER-Net observations report
  47. GRB 260915A: VLT optical and near-infrared upper limits
  48. EP260917a: refined analysis of the EP-FXT observations
  49. EP260806a: Yamaguchi Interferometer radio detections
  50. GRB 260918A: SVOM/C-GFT optical upper limits
  51. EP Alert 260918.62: Global MASTER-Net observations report
  52. Fermi GBM Sub-Threshold Detection of GRB 260918A
  53. EP Alert 260918.24: Global MASTER-Net observations report
  54. SVOM GRB260918.16: Global MASTER-Net observations report
  55. EP260917b: EP-WXT detection of an X-ray transient
  56. EP260917A: J-band upper limit with WINTER
  57. EP Alert 260917.32: Global MASTER-Net observations report
  58. GRB 260915A: Swift-XRT afterglow detection
  59. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. GRB 260918A: SVOM detection of a burst
  61. GRB 260915A: SVOM/ECLAIRs refined analysis
  62. GRB 260917B: WINTER J-band observations
  63. GRB 260917B: SVOM/VT optical observations
  64. SVOM GRB260917.16: Global MASTER-Net observations report
  65. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  66. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  67. Fermi trigger No 811304653: Global MASTER-Net observations report
  68. GRB 260915A: J-band upper limit with WINTER
  69. Fermi trigger No 811264269: Global MASTER-Net observations report
  70. GRB 260909A: NOEMA detection
  71. GRB 260914A: Mondy and TShAO optical observations
  72. GRB 260914A: SVOM/ECLAIRs refined analysis
  73. GRB 260909A: Swift-XRT observations
  74. MAXI GRB260916.37: Global MASTER-Net observations report
  75. GRB 260915A: Swift ToO observations
  76. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  77. GRB 260915A: SVOM/C-GFT optical upper limits
  78. GRB 260915A: REM optical/NIR observations
  79. GRB 260914A: REM optical/NIR observations
  80. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  81. GRB 260915A: SVOM/VT optical upper limits
  82. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  83. GRB 260915A: NOT optical upper limit
  84. SVOM GRB260915.05: Global MASTER-Net observations report
  85. GRB 260915A: SVOM/VT optical upper limits from VHF data
  86. Fermi GBM Sub-Threshold Detection of GRB 260915A
  87. EP Alert 260914.53: Global MASTER-Net observations report
  88. Fermi GBM Sub-Threshold Detection of GRB 260914A
  89. GRB 260914A: LCO optical observation
  90. GRB 260914A: SVOM/C-GFT optical observations
  91. GRB 260914A: SVOM/VT optical counterpart confirmation
  92. GRB 260914A: SVOM/VT optical observation from VHF data
  93. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  94. SVOM GRB260914.47: Global MASTER-Net observations report
  95. GRB 260818A: Continued ATCA observations
  96. SVOM GRB260913.32: Global MASTER-Net observations report
  97. GRB 260913A: SVOM/C-GFT optical upper limit
  98. GRB 260909A: CrAO and AbAO optical upper limits
  99. GRB 260909A: SVOM/ECLAIRs refined analysis
  100. GRB 260910B: GOTO tentative optical counterpart candidates

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov