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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 241026A: radio detection with the VLA
  2. EP241125a: Optical upper limit with Kinder observations
  3. EP241125a: EP detection of an X-ray transient
  4. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  5. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  6. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  7. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  8. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  9. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  10. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  11. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  12. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  13. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  14. GRB 241120A: GRBAlpha detection
  15. GRB 241113B: SVOM/VT optical afterglow observations
  16. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  17. Konus-Wind detection of GRB 241117A
  18. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  19. GRB 241105A: ATCA radio detection
  20. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  21. IPN triangulation of GRB 241117A
  22. GRB 241026A: VIRT Optical Upper Limit
  23. GRB 241025A: VIRT Optical Upper Limit
  24. Konus-Wind detection of GRB 241120A
  25. GRB241120A: OHP/T193 optical observations
  26. GRB 241120A: CALET Gamma-Ray Burst Monitor detection
  27. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  28. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  29. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  30. GRB 241120A: Mondy and AbAO optical observations
  31. EP241119a: Optical upper limits with Kinder observations
  32. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  33. EP241119a: GIT optical upper limits
  34. GRB 241113A: Possible ATCA Radio detection
  35. EP241119a : J-band observations with WINTER
  36. GRB 241120A: Fermi GBM Observation
  37. GRB 241114B: Insight-HXMT/HE detection
  38. Integral GRB241120.25: Global MASTER-Net observations report
  39. EP241119a: Global MASTER-Net observations report
  40. EP241119a: EP detection of a fast X-ray transient
  41. GRB241120A: a long GRB detected by INTEGRAL
  42. GRB 241120A: Fermi GBM Final Real-time Localization
  43. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  44. GRB 241112B: Mephisto further optical observations
  45. GRB 241119A: Fermi GBM Final Real-time Localization
  46. GRB 241030A: J-band observations
  47. GRB 241115a: PRIME near-infrared upper limits
  48. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  49. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  50. GRB 241115B: Fermi GBM Observation
  51. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  52. Fermi GRB 241118A: Global MASTER-Net observations report
  53. GRB 241118A: Fermi GBM Final Real-time Localization
  54. Updates to IceCube realtime alert system for muon tracks
  55. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  56. GRB 241117A: Fermi GBM Detection
  57. Fermi GRB 241117B: Global MASTER-Net observations report
  58. GRB 241117B: Fermi GBM Final Real-time Localization
  59. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  60. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  61. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  62. Fermi GRB 241117A: Global MASTER-Net observations report
  63. GRB 241117A: Fermi GBM Final Real-time Localization
  64. GRB 241115C: Fermi GBM Observation
  65. GRB 241115A: Swift-XRT afterglow detection
  66. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  67. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  68. GRB 241115A: Mephisto upper limits
  69. GRB 241113B: Mephisto upper limits
  70. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  71. GRB 241115D / EP 241115a: SVOM/GRM observation
  72. The EP-WXT trigger 01709120856 is likely a flaring star
  73. EP241113a: Swift XRT weak detection
  74. GRB 241115A: Fermi GBM Observation
  75. GRB 241115A: LCOGT Optical Upper Limits
  76. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  77. Fermi GRB 241115B: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  79. EP241115a: Global MASTER-Net observations report
  80. GRB 241115B: Fermi GBM Final Real-time Localization
  81. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  82. EP241115a: EP detection of a fast X-ray transient
  83. EP241113a: No Detection in Fermi-GBM Observations
  84. Swift GRB 241115A: Global MASTER-Net observations report
  85. Fermi GRB 241115A: Global MASTER-Net observations report
  86. GRB 241115A: Swift detection of a burst
  87. GRB 241115A: Fermi GBM Final Real-time Localization
  88. EP 241113a: LBT possible optical counterpart
  89. GRB 241113B: KAIT Optical Afterglow Candidate
  90. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  91. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  92. GRB 241113A: Swift-BAT refined analysis
  93. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  94. GRB 241113A: PRIME near-infrared upper limits
  95. Fermi GRB 241114A: Global MASTER-Net observations report
  96. EP241113a: Global MASTER-Net observations report
  97. GRB 241114A: Fermi GBM Final Real-time Localization
  98. GRB 241113B: J-band upper limit from WINTER
  99. GRB 241113A: J-band observations with WINTER
  100. EP241113a : J-band observations with WINTER

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