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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

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. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  2. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S240919bn: GOTO optical upper limits
  5. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  6. GRB 240918B: AstroSat CZTI detection
  7. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  9. EP240919a: EP-FXT follow-up observation update
  10. EP240913A/GRB 240913C: AbAO optical upper limit
  11. EP240919a / GRB 240919A: Mondy optical upper limit
  12. EP240913a/GRB 240913C: 1.6m Mephisto observations
  13. EP240918a: SVOM/VT upper limit
  14. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  15. EP240919a / GRB 240919A: REM optical and NIR upper limits
  16. EP240919a / GRB 240919A: KAIT optical upper limit
  17. EP240918b and EP240918c: Optical upper limits with Kinder observations
  18. GRB 240414A: further radio observations with the VLA
  19. EP240919a: Optical upper limit with Kinder observations
  20. GRB 240919A / EP240919a: SVOM/GRM observation
  21. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  22. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  23. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  24. EP EP240919a: Global MASTER-Net observations report
  25. GRB 240910A: radio detection with the VLA
  26. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  27. EP240919a: NOT and Gemini optical observations
  28. EP240919a: GOTO optical upper limits
  29. EP240919a: JinShan optical upper limits
  30. EP240919a is likely a GRB event (duplicate submission of 37563)
  31. EP240919a is likely a GRB event
  32. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  33. EP240919a: EP-WXT detection of a fast X-ray transient
  34. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  35. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  36. GRB 240918B: Fermi GBM Detection
  37. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  38. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  39. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  40. EP240918a: EP observation update
  41. GRB 240910A: further Swift observations and confirmation of afterglow
  42. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  43. EP240918a: Swift-XRT observation
  44. Fermi GRB 240918A: Global MASTER-Net observations report
  45. GRB 240918A: Fermi GBM Final Real-time Localization
  46. EP EP240918a: Global MASTER-Net observations report
  47. EP240918a: JinShan optical upper limits
  48. EP240918a: YAHPT Optical Upper Limit
  49. EP240918a: Optical upper limits with Kinder observations
  50. EP240918a: GMG Optical Upper Limit
  51. GRB 240916A: GRBAlpha detection
  52. GRB 240914B: GRBAlpha detection
  53. EP240918a: an X-ray transient detected by Einstein Probe
  54. GRB 240916A: NOT optical observation
  55. GRB 240912A: Swift-BAT refined analysis
  56. IPN triangulation of GRB 240913C / EP 240913a
  57. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  58. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  59. GRB 240916A: Fermi GBM Observation
  60. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  61. GRB 240821A: radio observation with the VLA
  62. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  63. GRB 240916A: Swift-XRT afterglow detection
  64. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  65. GRB 240916A: Swift ToO observations
  66. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  67. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  68. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  69. GRB 240916B: Fermi GBM Final Real-time Localization
  70. GRB 240914B: Fermi GBM Final Localization
  71. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  72. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  73. EP EP240913a: Global MASTER-Net observations report
  74. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  75. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  76. GRB 240916A: Fermi GBM Final Real-time Localization
  77. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  78. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  79. EP240913a: VLT/HAWK-I near-infrared upper limits
  80. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  82. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  83. EP240913a/GRB 240913C: KAIT optical upper limit
  84. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  85. GRB 240913C: Fermi GBM detection
  86. GRB 240914A: Swift-XRT observations
  87. GRB 240913C: Joint location by ETJASMIN
  88. GRB 240914B: AstroSat CZTI detection
  89. EP240913A / GRB 240913C: AstroSat CZTI detection
  90. GRB 240914A: SVOM/GRM observation
  91. GRB 240910A: SVOM/VT optical observations
  92. GRB 240914A: Swift ToO observations
  93. EP240913a: NOT optical upper limits
  94. EP240913a: JinShan optical upper limits
  95. EP240913a: ESO-NTT optical observations
  96. GRB 240914A: ESO-NTT optical observations
  97. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  98. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  99. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  100. GRB 240905E: further NOT optical observations

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