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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"

28275 results found.

  1. GRB 250101A: CMO RC-500 optical observations
  2. GRB 250109A: Fermi GBM Observation
  3. EP250108a: NOT optical observations
  4. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  5. GRB 250109a: GMG Optical Upper Limit
  6. EP250109a: Swift/UVOT non-detection
  7. IPN triangulation of GRB 250107D (short/hard)
  8. EP250108a: Liverpool Telescope likely optical counterpart
  9. GRB 250108B: Swift-BAT refined analysis
  10. GRB 250108B: 1.3m DFOT upper limit
  11. GRB 250108B: REM optical/NIR upper limits
  12. GRB 250101A: Terskol K-800 optical observations
  13. EP250109a: Swift/XRT non-detection
  14. GRB 250108A: Swift/UVOT Upper Limits
  15. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  16. GRB 250108A: NOT optical upper limit
  17. EP250108a: EP-WXT detection of an X-ray transient
  18. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  19. GRB 250108B: Swift-XRT refined Analysis
  20. GRB 250103A: 1.6m Mephisto optical observations
  21. GRB 250108A: Swift-XRT afterglow detection
  22. GRB 250108A:SVOM/VT optical candidate
  23. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  24. GRB 250108B: Swift/UVOT Upper Limits
  25. GRB 250103A: Swift-XRT afterglow detection
  26. GRB 250108B: Enhanced Swift-XRT position
  27. GRB 250108B: Swift detection of a burst
  28. GRB 250107A: Fermi GBM Observation
  29. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  30. GRB 250106A: SVOM/VT 2nd optical deep observation
  31. GRB 250101A: J band upper limit by SYSU 80cm telescope
  32. EPWXT01709129925: Xinglong optical observations
  33. GRB 250106A: NOT optical observations
  34. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  35. GRB 250103B: REM optical/NIR upper limits
  36. GRB 250101A: REM optical/NIR counterpart detection
  37. GRB 250106A: Swift-XRT observations
  38. GRB 250106A: SVOM/VT optical candidate
  39. The EP-WXT trigger 01709129925 is likely a flaring star
  40. GRB 250103B: Swift-XRT refined Analysis
  41. GRB 250103B: LCO/1m optical afterglow candidate detection
  42. GRB 250103A: Bassano Bresciano Observatory upper limit
  43. GRB 250103A: Swift-XRT observations
  44. GRB 250101A: 1.3m DFOT optical afterglow detection
  45. GRB 241229A: 1.3m DFOT upper limit
  46. GRB 241228B: 1.3m DFOT Optical observations
  47. GRB 241228A: 1.3m DFOT upper limit
  48. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  49. GRB 250103A: Montarrenti Observatory optical detection
  50. GRB 250101A: further LCOGT optical afterglow observations
  51. GRB 250103A: TSHAO optical upper limit
  52. GRB 250103A: Fermi GBM Observation
  53. GRB 250103B: LCOGT Optical Upper Limit
  54. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  55. EP250101a: Liverpool Telescope optical upper limit
  56. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 250101a: Liverpool Telescope optical follow-up
  58. GRB 250103B: Swift detection of a burst
  59. GRB 250103A: Xinglong 2.16m Optical Candidate
  60. GRB 250101B: SVOM/GRM observation
  61. GRB 250103A: GOTO optical upper limit
  62. GRB 250103A: SVOM/C-GFT optical upper limit
  63. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  64. EP241231b: optical upper limit with the Liverpool Telescope
  65. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  66. GRB 250103A: SVOM detection of a long burst
  67. EP250101a: Xinglong optical upper limit
  68. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  69. GRB 250101A: Swift-BAT refined analysis
  70. GRB 250101A: further SAO RAS optical observations
  71. GRB 250101A: LCO optical counterpart detection
  72. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  73. GRB 250101A: Swift/UVOT Detection
  74. GRB 250101A: 1.6m Mephisto multi-band optical followup
  75. GRB 250101A: Swift-XRT refined Analysis
  76. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  77. GRB 250101A: LCOGT optical afterglow detection
  78. GRB 250101A: OASDG optical observations
  79. GRB 250101B: Fermi GBM Final Real-time Localization
  80. GRB 250101A: SAO RAS observations of optical brightening
  81. GRB 250101A: BOOTES-4/MET optical afterglow detection
  82. GRB 250101A: AKO Optical Afterglow Detection
  83. GRB 250101A: SAO RAS optical observations
  84. GRB 250101A: Enhanced Swift-XRT position
  85. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  86. GRB 250101A: SVOM/C-GFT early optical observations
  87. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  88. GRB 250101A: Nanshan/HMT optical observations
  89. GRB 250101A : GIT optical detection
  90. GRB 250101A: GMG Optical Observation
  91. GRB 250101A: Swift detection of a burst with an optical counterpart
  92. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  93. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  94. GRB 241229B: Continued CrAO ZTSh observations
  95. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  96. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  97. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  98. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  99. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  100. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto

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