Skip to main content
Announcing GCN Classic Migration Survey, End of Legacy Circulars Email. 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. GRB 241204A: Fermi GBM Observation
  2. Fermi GRB 241204A: Global MASTER-Net observations report
  3. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  4. GRB 241128A : RAPAS follow-up observations
  5. GRB 241201A: GRBAlpha detection
  6. GRB 241204A: Fermi-LAT detection
  7. EP241202b: Upper limits from Fermi-GBM Observations
  8. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  9. EP241202b: Kinder optical counterpart candidate
  10. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  11. GRB 241113B : RAPAS follow-up observation
  12. EP241201a: EP-FXT follow-up observations
  13. Konus-Wind detection of GRB 241130A
  14. EP241202b: Global MASTER-Net observations report
  15. EP241201a: BOOTES-5 optical upper limit
  16. EP241202b: EP detection of a fast X-ray transient
  17. EP241201a: NOT optical observations
  18. IPN triangulation of GRB 241130A
  19. GRB 241130A: EIRSAT-1 GMOD Detection
  20. GRB 241128A: Swift/UVOT Upper Limits
  21. GRB 241130A: Fermi GBM Detection
  22. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  24. EP241201a: Kinder optical counterpart candidate
  25. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  26. EP241201a: Global MASTER-Net observations report
  27. EP241201a: EP detection of a fast X-ray transient
  28. The EP-WXT trigger 01709126243 is not a real source
  29. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  30. GRB241201B: Fermi GBM Final Localization
  31. GRB241201B: Fermi GBM Final Localization
  32. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  33. EP241126a: SOAR observations of the optical counterpart
  34. Fermi GRB 241201A: Global MASTER-Net observations report
  35. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  36. GRB 241130A: Fermi GBM Final Real-time Localization
  37. GRB 241130A: Fermi GBM Final Real-time Localization
  38. EP241126a: 1.6m Mephisto Optical Upper Limits
  39. GRB 241201A: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  42. Fermi trigger No 754701230: Global MASTER-Net observations report
  43. IPN triangulation of GRB 241128B
  44. Konus-Wind detection of GRB 241114B
  45. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  46. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  47. GRB 241128A: AbAO optical upper limit
  48. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  49. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  51. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  52. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  53. GRB 241128C: SVOM/GRM observation
  54. GRB 241128B: SVOM/GRM observation
  55. GRB 241128A: Swift-BAT refined analysis
  56. GRB 241127A: Swift-BAT refined analysis
  57. EP241126a: NOT optical observations
  58. GRB 241127A: PRIME near-infrared detection
  59. GRB 241128A: Mondy optical observations
  60. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  61. Swift-XRT observations of IceCube -241127A
  62. Swift GRB 241128A: Global MASTER-Net observations report
  63. Fermi-LAT gamma-ray observations of IceCube-241127A
  64. EP241126a: SVOM/VT observations
  65. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  66. GRB 241128A: Swift-XRT refined Analysis
  67. GRB 241129A: Fermi GBM Final Real-time Localization
  68. GRB 241128A: Enhanced Swift-XRT position
  69. GRB 241128A: NOT optical observations
  70. GRB 241128A: LCO optical detection
  71. GRB 241128A: 1.5m OSN optical afterglow detection
  72. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  73. Fermi trigger No 754492985: Global MASTER-Net observations report
  74. GRB 241128A: Swift-XRT afterglow detection
  75. GRB 241128A: Swift detection of a burst
  76. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  77. GRB 241127A: Swift/UVOT Detection
  78. GRB 241127A: Swift-XRT refined Analysis
  79. GRB 241127A: SVOM/GRM observation
  80. GRB 241127A: Enhanced Swift-XRT position
  81. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  82. The EP-WXT trigger 01709125191 is not a real source
  83. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  84. Swift GRB241127.91: Global MASTER-Net OT detection
  85. EP241126a: WFST Observations
  86. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  87. IceCube Alert 241127.59: Global MASTER-Net observations report
  88. GRB 241127A: Swift detection of a burst with an optical counterpart
  89. Swift GRB241127.91: Global MASTER-Net observations report
  90. Swift GRB241127.91: Global MASTER-Net OT detection
  91. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  92. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  93. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  94. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  95. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  96. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  97. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  98. EP241126a: Optical Upper limits with Kinder observations
  99. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  100. GRB 241126A: SVOM/GRM observation

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