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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').
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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"
  1. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  2. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  3. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  4. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  5. EP241126a: Optical Upper limits with Kinder observations
  6. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  7. GRB 241126A: SVOM/GRM observation
  8. IPN triangulation of GRB 241114B
  9. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  10. EP241126a: EP-FXT follow-up observation update
  11. EP241126a: GSP detects optical counterpart
  12. EP241126a: TRT optical counterpart detection
  13. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  14. EP241126a: EP detection of a fast X-ray transient
  15. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  16. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  17. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  18. Trigger_18947: Swift ToO observations (retracted)
  19. GRB 241113B: EP-FXT afterglow detection
  20. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  21. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  22. SVOM/GRM detection of a short burst from SGR 1830
  23. GECAM detection of a short burst from SGR 1830
  24. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  25. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  26. Konus-Wind detection of GRB 241115D / EP 241115a
  27. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  28. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  29. GRB 241026A: radio detection with the VLA
  30. EP241125a: Optical upper limit with Kinder observations
  31. EP241125a: EP detection of an X-ray transient
  32. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  33. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  34. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  35. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  36. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  37. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  38. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  39. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  40. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  41. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  42. GRB 241120A: GRBAlpha detection
  43. GRB 241113B: SVOM/VT optical afterglow observations
  44. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  45. Konus-Wind detection of GRB 241117A
  46. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  47. GRB 241105A: ATCA radio detection
  48. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  49. IPN triangulation of GRB 241117A
  50. GRB 241026A: VIRT Optical Upper Limit
  51. GRB 241025A: VIRT Optical Upper Limit
  52. Konus-Wind detection of GRB 241120A
  53. GRB241120A: OHP/T193 optical observations
  54. GRB 241120A: CALET Gamma-Ray Burst Monitor detection
  55. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  56. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  57. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  58. GRB 241120A: Mondy and AbAO optical observations
  59. EP241119a: Optical upper limits with Kinder observations
  60. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  61. EP241119a: GIT optical upper limits
  62. GRB 241113A: Possible ATCA Radio detection
  63. EP241119a : J-band observations with WINTER
  64. GRB 241120A: Fermi GBM Observation
  65. GRB 241114B: Insight-HXMT/HE detection
  66. Integral GRB241120.25: Global MASTER-Net observations report
  67. EP241119a: Global MASTER-Net observations report
  68. EP241119a: EP detection of a fast X-ray transient
  69. GRB241120A: a long GRB detected by INTEGRAL
  70. GRB 241120A: Fermi GBM Final Real-time Localization
  71. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  72. GRB 241112B: Mephisto further optical observations
  73. GRB 241119A: Fermi GBM Final Real-time Localization
  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 241115B: Fermi GBM Observation
  79. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  80. Fermi GRB 241118A: Global MASTER-Net observations report
  81. GRB 241118A: Fermi GBM Final Real-time Localization
  82. Updates to IceCube realtime alert system for muon tracks
  83. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  84. GRB 241117A: Fermi GBM Detection
  85. Fermi GRB 241117B: Global MASTER-Net observations report
  86. GRB 241117B: Fermi GBM Final Real-time Localization
  87. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  88. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  89. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  90. Fermi GRB 241117A: Global MASTER-Net observations report
  91. GRB 241117A: Fermi GBM Final Real-time Localization
  92. GRB 241115C: Fermi GBM Observation
  93. GRB 241115A: Swift-XRT afterglow detection
  94. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  95. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  96. GRB 241115A: Mephisto upper limits
  97. GRB 241113B: Mephisto upper limits
  98. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  99. GRB 241115D / EP 241115a: SVOM/GRM observation
  100. The EP-WXT trigger 01709120856 is likely a flaring star

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