Skip to main content
GCN at AAS 245, Legacy Circulars Address Retirement. 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').
  1. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  2. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  3. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  4. GRB 241120A: Mondy and AbAO optical observations
  5. EP241119a: Optical upper limits with Kinder observations
  6. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  7. EP241119a: GIT optical upper limits
  8. GRB 241113A: Possible ATCA Radio detection
  9. EP241119a : J-band observations with WINTER
  10. GRB 241120A: Fermi GBM Observation
  11. GRB 241114B: Insight-HXMT/HE detection
  12. Integral GRB241120.25: Global MASTER-Net observations report
  13. EP241119a: Global MASTER-Net observations report
  14. EP241119a: EP detection of a fast X-ray transient
  15. GRB241120A: a long GRB detected by INTEGRAL
  16. GRB 241120A: Fermi GBM Final Real-time Localization
  17. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 241112B: Mephisto further optical observations
  19. GRB 241119A: Fermi GBM Final Real-time Localization
  20. GRB 241030A: J-band observations
  21. GRB 241115a: PRIME near-infrared upper limits
  22. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  23. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  24. GRB 241115B: Fermi GBM Observation
  25. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  26. Fermi GRB 241118A: Global MASTER-Net observations report
  27. GRB 241118A: Fermi GBM Final Real-time Localization
  28. Updates to IceCube realtime alert system for muon tracks
  29. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  30. GRB 241117A: Fermi GBM Detection
  31. Fermi GRB 241117B: Global MASTER-Net observations report
  32. GRB 241117B: Fermi GBM Final Real-time Localization
  33. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  34. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  35. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  36. Fermi GRB 241117A: Global MASTER-Net observations report
  37. GRB 241117A: Fermi GBM Final Real-time Localization
  38. GRB 241115C: Fermi GBM Observation
  39. GRB 241115A: Swift-XRT afterglow detection
  40. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  41. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  42. GRB 241115A: Mephisto upper limits
  43. GRB 241113B: Mephisto upper limits
  44. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  45. GRB 241115D / EP 241115a: SVOM/GRM observation
  46. The EP-WXT trigger 01709120856 is likely a flaring star
  47. EP241113a: Swift XRT weak detection
  48. GRB 241115A: Fermi GBM Observation
  49. GRB 241115A: LCOGT Optical Upper Limits
  50. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  51. Fermi GRB 241115B: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  53. EP241115a: Global MASTER-Net observations report
  54. GRB 241115B: Fermi GBM Final Real-time Localization
  55. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  56. EP241115a: EP detection of a fast X-ray transient
  57. EP241113a: No Detection in Fermi-GBM Observations
  58. Swift GRB 241115A: Global MASTER-Net observations report
  59. Fermi GRB 241115A: Global MASTER-Net observations report
  60. GRB 241115A: Swift detection of a burst
  61. GRB 241115A: Fermi GBM Final Real-time Localization
  62. EP 241113a: LBT possible optical counterpart
  63. GRB 241113B: KAIT Optical Afterglow Candidate
  64. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  65. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  66. GRB 241113A: Swift-BAT refined analysis
  67. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  68. GRB 241113A: PRIME near-infrared upper limits
  69. Fermi GRB 241114A: Global MASTER-Net observations report
  70. EP241113a: Global MASTER-Net observations report
  71. GRB 241114A: Fermi GBM Final Real-time Localization
  72. GRB 241113B: J-band upper limit from WINTER
  73. GRB 241113A: J-band observations with WINTER
  74. EP241113a : J-band observations with WINTER
  75. GRB 241030A: LCO optical observation
  76. GRB 241113B: Swift-XRT observations
  77. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  79. GRB 241113A: KAIT optical observations
  80. EP241113b: Global MASTER-Net observations report
  81. EP241113b/GRB 241113B: EP detection of GRB 241113B
  82. Fermi-LAT gamma-ray observations of IceCube-241113A
  83. GRB 241113B: SVOM/GRM observation
  84. EP241113a: EP on-board trigger and autonomous follow-up observation
  85. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  86. GRB 241113A: Swift-XRT refined Analysis
  87. EP241107a: SOAR upper limits
  88. GRB 241113A: Swift/UVOT Detection
  89. GRB 241113A: REM detection of the optical/NIR afterglow
  90. Konus-Wind detection of GRB 241107A (short/hard)
  91. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  92. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  93. GRB 241113B: Swift ToO observations
  94. GRB 241113A: LCO optical observations
  95. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 241112B: GMG Optical Upper Limit
  97. GRB 241113A: Enhanced Swift-XRT position
  98. GRB241113A: LCOGT (40-cm) optical counterpart detection
  99. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  100. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection

Advanced

Download all Circulars as a .tar.gz archive:
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