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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').

18688 results found.

  1. EP241201a: NOT optical observations
  2. GRB 241128A: Swift/UVOT Upper Limits
  3. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  4. EP241201a: Kinder optical counterpart candidate
  5. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  6. EP241126a: 1.6m Mephisto Optical Upper Limits
  7. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  8. Konus-Wind detection of GRB 241114B
  9. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  10. GRB 241128A: AbAO optical upper limit
  11. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  13. GRB 241127A: PRIME near-infrared detection
  14. GRB 241128A: Mondy optical observations
  15. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  16. Swift-XRT observations of IceCube -241127A
  17. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  18. GRB 241128A: Enhanced Swift-XRT position
  19. GRB 241128A: NOT optical observations
  20. GRB 241128A: LCO optical detection
  21. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  22. GRB 241128A: Swift-XRT afterglow detection
  23. GRB 241128A: Swift detection of a burst
  24. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  25. GRB 241127A: Swift/UVOT Detection
  26. GRB 241127A: Enhanced Swift-XRT position
  27. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  28. Swift GRB241127.91: Global MASTER-Net OT detection
  29. EP241126a: WFST Observations
  30. GRB 241127A: Swift detection of a burst with an optical counterpart
  31. Swift GRB241127.91: Global MASTER-Net OT detection
  32. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  33. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  34. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  35. EP241126a: Optical Upper limits with Kinder observations
  36. IPN triangulation of GRB 241114B
  37. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  38. EP241126a: GSP detects optical counterpart
  39. EP241126a: TRT optical counterpart detection
  40. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  41. EP241126a: EP detection of a fast X-ray transient
  42. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  43. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  44. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  45. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  46. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  47. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  48. Konus-Wind detection of GRB 241115D / EP 241115a
  49. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  50. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  51. GRB 241026A: radio detection with the VLA
  52. EP241125a: Optical upper limit with Kinder observations
  53. EP241125a: EP detection of an X-ray transient
  54. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  55. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  56. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  57. GRB 241120A: GRBAlpha detection
  58. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  59. Konus-Wind detection of GRB 241117A
  60. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  61. IPN triangulation of GRB 241117A
  62. GRB 241026A: VIRT Optical Upper Limit
  63. GRB 241025A: VIRT Optical Upper Limit
  64. GRB241120A: OHP/T193 optical observations
  65. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  66. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  67. GRB 241120A: Mondy and AbAO optical observations
  68. EP241119a: Optical upper limits with Kinder observations
  69. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  70. EP241119a: GIT optical upper limits
  71. EP241119a : J-band observations with WINTER
  72. EP241119a: EP detection of a fast X-ray transient
  73. GRB 241112B: Mephisto further optical observations
  74. GRB 241030A: J-band observations
  75. GRB 241115a: PRIME near-infrared upper limits
  76. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  77. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  78. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  79. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  80. GRB 241115A: Swift-XRT afterglow detection
  81. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  82. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  83. GRB 241115A: Mephisto upper limits
  84. GRB 241113B: Mephisto upper limits
  85. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  86. GRB 241115D / EP 241115a: SVOM/GRM observation
  87. EP241113a: Swift XRT weak detection
  88. GRB 241115A: LCOGT Optical Upper Limits
  89. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  90. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  91. EP241115a: EP detection of a fast X-ray transient
  92. Swift GRB 241115A: Global MASTER-Net observations report
  93. Fermi GRB 241115A: Global MASTER-Net observations report
  94. GRB 241115A: Swift detection of a burst
  95. EP 241113a: LBT possible optical counterpart
  96. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  97. GRB 241113A: PRIME near-infrared upper limits
  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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